CHANGING CONCENTRATION

In this reaction, all the substances are in the equilibrium. The proportion of the substances are constant, although there is still a forward reaction and reverse reaction. This microscopic change we couldn't see.
However, we can change this constant proportion by changing the concentration, for example by adding A, we increase the concentration of A. When [A]>, the collision between A and B caused the the rate of forward reaction > the rate of reverse reaction. The position of equilibrium lies to the right, because the equilibrium shifts to the right. When we increase [C], the equilibrium shifts to the left. When we decrease [D], the equilibrium shifts to the right.
According to the Le Chatelier Principle, when in the equilibrium we give an action, so the equilibrium will give back an action which named as a reaction to achieve the new equilibrium, so the process will be constant again.

THE EFFECT OF TEMPERATURE ON REACTION RATES

In a certain reaction, the reactants need an amount of energy, because their molecular energy is low, but the activation energy is high.
This type of reaction named as endotermic reaction (remember the concept of thermochemistry)
To achieve the best collision, you have to heat the reactants in order to increase the the molecular energy till the same as the activation energy. At that point, the reaction will occur.

ADDING CATALYST

Le Chatelier's Principle and catalysts

If you add a catalyst in the reversible reaction that in the equilibrium condition, so you do nothing. Its mean that the catalyst doesn't make any changing. Catalyst couldn' shift the position of equilibrium.
Do you remember what for the catalyst used as one of the factors affecting the reaction rate? The catalyst can speeds up the reaction, okay.
Now please think about the reversible reaction. There are two directions, the forward and reverse reactions. In the reversible reaction, if you add the catalyst before reaction, it will speed up the forward reaction and and immediately, the catalyst also speed up the reverse reaction till the rate reactions of both directions are the same, so there is a dynamic equilibrium. The dynamic equilibrium will be occured faster in the exist of catalyst. If you add catalyst in an equilibrium condition, it can affect the position of equilibrium.
A lot of dynamic equilibrium is very slow. This will cause of big problems in industrial processes. So the catalyst is still needed.

CHANGING TEMPERATURE

Using Le Chatelier's Principle with a change of temperature
Students, remember that in discussing the reaction rate, temperature is also one of the factors which affect the reaction rate.
If we think about changing temperature, so we have to look at the dynamic equilibrium, check the forward reaction, endotermic or exotermic.
If the forward reaction is endotermic, the sign of enthalpy change is positive. If the temperature is increased, what will happen? The endotermic reaction is a reaction which the reactants absorb the heat. So the kinetic energy of the reactants will increase and the number of efective collision will increase. Because of this, the reaction rate of the forward reaction is greater than the reverse reaction, so that the equilibrium will shift to the right and the concentration of products increase. The equilibrium constant is greater than the initial.
For another equilibrium, if the forward reaction is exothermic, the sign of enthalpy change is negative. The reverse reaction is endothermic and the sign of enthalpy is positive. If the temperature is increased, the products will absorb the energy and their kinetic energy will increase. The reaction rate of the reverse reaction is greater than the forward reaction. So the equilibrium will shift to the endotermic reaction, so it will shift to the left and the concentration of reactants increase; the equilibrium constant is smaller than before.
Why does the endothermic reaction absorb the energy when we increase the temperature?
According to Le Chatelier, the position of equilibrium will shift to counteract the change. This means that the position of equilibrium will shift so that the temperature is reduced again. (Action and reaction)
If the temperature of an equilibrium system is 200°C, and we increase the temperature to 300°C, what will happen? How can the reaction counteract the change we have made? What the reaction of this action? The reaction is there is a cooling down, to make the temperature reduces. The reactants will absorb the energy (heat) that we put in, so the equilibrium shift to the endothermic reaction.

CHANGING PRESSURE

Using Le Chatelier's Principle with a change of pressure

Lets discuss about changing pressure in reactions involving gases
What would happen if the condition of an equilibrium is changed by increasing the pressure?
According to Le Chatelier, the position of equilibrium will shift to a certain direction to counteract the change. That means that the position of equilibrium will shift so that the pressure is reduced again (If there is an action, there is a reaction).
The more molecules in the container, the higher the pressure will be. The system can reduce the pressure by reacting in such a way to produce fewer molecules.
For example : N2(g)+ 3H2(g) = 2NH3(g)
In this reaction, there are 4 molecules on the left-hand side of the equation, but only 2 on the right. By forming more NH3, the system causes the pressure to reduce.
Increasing the pressure on a gas reaction shifts the position of equilibrium towards the side with fewer molecules.
In summary, when P >, Volume <, equilibrium shift to the fewer molecules. N2 and H2 molecules are closely, the efective collision increases, the rate of forward reaction increases. The equilibrium will achieve after the rate of forward reaction = the rate of reverse reaction. The value of equilibrium constant is the same. What would happen if the condition of equilibrium is changed by decreasing the pressure? The equilibrium will shift to the left, because P <, Volume >, equilibrium will shift to the more molecules, e.i. N2 and H2 molecules.
Another example : H2(g) + I2(g) = 2HI(g).
In the above equilibrium, the number of molecules in the both sides are the same. What happens if P > ?
Increasing the pressure has no effect on the position of the equilibrium, because there are the same numbers of molecules on both sides.

LE CHATELIER'S PRINCIPLE

Now lets discuss about Le Chatelier's Principle. This scientist have investigated a dynamic equilibrium. He disturbed an equilibrium reaction by changing the condition of the reaction. When he changes the concentration of a reactant, from the color of the color of the substances he found that the color change. He disturbs both side, one by one, reactant and product.
From his finding, when a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change.
Okay, now we use Le Chatelier's Principle with a change of concentration
For example an equilibrium reaction : A + B = C + D.
What would happen if you changed the conditions by increasing the concentration of A? According to Le Chatelier, the position of equilibrium will shifts to counteract the change. It means the position of equilibrium will shift, so the concentration of A decreases, because it reacts with B and it turns into C + D. The position of equilibrium shifts to the right. So if concentration of the left increases, the equilibrium shifts to the right. The Le Chatelier principle is very useful for industries, because this evidence can help them to determine which substance should be added to make the high profit. So they have to think an economical judgment. They have to find the cheapest raw materials rather than the expensive one.
Now, what would happen if you changed the conditions by decreasing the concentration of D (You remove the product from the equilibrium)?
The position of equilibrium will shift so that the concentration of D increases. It means that more A and B will react to replace the D that has been removed. The position of equilibrium shifts to the right. So if concentration of the right decreases, the equilibrium shift to the right.

DYNAMIC EQUILIBRIA

Reversible reaction is a reaction that can be occured in two directions, forward reaction and back (reverse) reaction. These reactions are happened at the same time.
Imagine a reaction : A(s) + B(aq) = C(aq) + D(g). This is in a closed system. We can think by using their color, for example B =blue and C = orange. At the same time blue --> orange and orange --> blue.
If the blue form turns into the orange one much faster than the the other one, so after the equilibrium can be achieved, the blue one becomes light and the orange one becomes dark. If this condition doesn't change again, the macroscopic change isn't happened but there is a dinamic change which is still occured constanously. This called a microscopic change and this reversible reaction named as a dynamic equilibrium.
Position of equilibrium
In the example above, the equilibrium mixture contained more orange than the blue ones. We can say :
"The position of equilibrium lies towards the orange."
"The position of equilibrium lies towards the right-hand side."
If the conditions of the experiment change (by adding reactant or product, so the macroscopic change will happen again), the composition of the equilibrium mixture will also change, till the equilibrium can be achieved.
Thinking about reaction rates
At the beginning of the reaction, the concentrations of A and B are at the maximum. The rate of the reaction is at its fastest.
As A and B react, their concentrations decrease, and the rate of the forward reaction falls as time goes on. At the same time, the concentration of C and D increases, and the rate of reverse reaction increases. At the equilibrium the rate of forward reaction= the rate of reverse reaction. (v1 = v2)

In summary, at equilibrium, the quantities of everything present in the mixture remain constant, although the reactions are still continuing. This is because the rates of the forward and the reverse reactions are equal.
If you change the conditions in a way which changes the relative rates of the forward and reverse reactions you will change the position of equilibrium or change the proportion of the subtances.
The charactheristic of dynamic equilibrium are :
1. Closed system
2. rate of forward reaction = rate of reverse reaction
3. Dynamic microscopic change
4. Constant proportion of substances

TYPES OF REACTION

There are two types of reaction, irreversible reaction and reversible reaction. The first reaction you have learnt till now. This reaction uses one arrow . This means that the reactants totally or completely react and form new substances.
This reaction is included neutralization, redox, decomposition, etc. In these reactions, all the reactants or one of the reactants are limited, after reaction no more reactants left or one of the reactant is nothing.
The second reaction uses two arrow; it means that the reaction can be occured in two directions, forward reaction and reverse reaction. This reaction can be occured in a closed system, so no substance will escape. If the reaction includes a gas, we have to close the equipment. If the reaction doesn' involve a gas, for example solid and liquid, so it doesn't need to close the equipment. The substances close theirselves. Because the closed system, so the reactants collide and form the products. At the same time the products collide and form the reactants again.
The example of both reactions are :
Zn(s) + HCl(aq) --> ZnCl2(aq) + H2(g) In the openned system.
N2(g) + 3 H2(g) = 2 NH3(g) In the closed system.

TYPES OF CATALYTIC REACTIONS

Catalysts can be divided into two main types - heterogeneous and homogeneous. In a heterogeneous reaction, the catalyst is in a different phase from the reactants, on the other hand, a homogeneous reaction, the catalyst is in the same phase as the reactants.
Look at the picture. The first is heterogeneous reaction, because there are two phases that you can see, liquid and solid. The catalyst is a solid phase and the reactants are liquid. So you see that there are two components in the different phases.

A mixture of various substances in a single solution consists of only one phase, because you can't see any boundary between them. They mix together homogeneously between reactants and catalyst.

THE EFFECT OF CATALYSTS ON REACTION RATES

Another factor that affects reaction rates named catalyst.
A catalyst is a substance which can speeds up a reaction, but is unchanged at the end of the reaction. The catalyst reacts in the intermediate process.
When certain reactants mix, the reaction is very slow. The possible reason is the activation energy is very high. The molecular energy is not enough. Last discussion, you heat the reactants to increase the molecular energy till the same as the activation energy. The work of catalyst differs. The catalyst will combine with one of the reactant and immediately the other reactant combine with the first. At that time, catalyst is separated and appeared again. This catalyst is exactly the same as before. The energy used to combine the reactants is the same as the molecular energy. This named as new activation energy. So this energy is lower than the original activation energy used in the reaction without catalyst.

THE BEST COLLISION FOR REACTION

When reactants start to react, they must have an enough energy for collision. This energy is named Activation Energy. This is a minimum amount of the energy required for best collision. Because of this energy, the bond between particles will break and each atoms will separate one of another. However, there is an important factor which should be taken into account, that is the right position of collision. Although the energy required is enough, if the collision is not in the right position, so reaction isn't occurred.
In conclusion, there are two important points for a collision to make reactants can start reaction. Please use this collision theory to explain factors that affect reaction rates.

COLLISION THEORY

According to the picture, why the first collision can make the reactants react one of another, and the second picture, there is a cross; its means that the reactants cannot react.

Is the position of collision very important point?

Is there any other reason to make the reactants react?

The third and the fourth pictures are impossible for reactants to react.

Why the position of molecules determines the best collision?

THE EFFECT OF PRESSURE ON DIFFERENT REACTIONS

Use this illustration for comparing reaction rates in different pressure.
For the above picture, both reactants are gases.
You can give an example to make clear your explanation.
After comparing gases, please compare the second picture.
In this reaction, one reactant is a solid. What happens with the rate in this condition? Give an example, becareful think about the properties of solid reactant.

THE EFFECT OF CONCENTRATION ON REACTION RATE

Hallo students, what do you think ab
out reaction rates?
This topic is simple, isn't it?
Okay, the first picture illustrates the reaction between particles in the solution. Water is as a solvent.
The second reaction is a reaction between solid and solution.
Firstly discuss the effect of concentration on reaction rate.
Secondly describe the effect of concentration of a solution when reacts with a solid reactant

THE EFFECT OF PRESSURE ON REACTION RATES

This moment we will discuss the change of pressure on reaction rates. The change of pressure only affects the rate of reaction involving gas. If the reaction involves solids or liquids, the change of pressure has no effect on the rate. Why thats difference? Think about the difference of the position of their particles.
What happens if you increase the pressure on a reaction involving gases?


Look at this equation. When you change the pressure, the number of molecules in certain volume also changes.

TEMPERATURE AND COLLISION THEORY

Please think that the change of temperature can affect the rate of reaction as shown in both pictures. By using collision theory, explain that A particles collide with B particles. It would be better if you make a plan first, than explain step by step clearly.
Becareful, this factor is temperature rather than concentration.

After make a conclusion, compare all the factors you have learnt and make a general conclusion by bringing all the factors.

FACTOR AFFECTING RATE OF REACTION

Look at both pictures. Compare these picture, explain which factor affects the rate of reaction?
Make a plan first, than write the data. Discuss your data and come to the conclusion, relate with your hypothesis. Don't forget to explain the variables.
Try to use collision theory in explaing the process.

Explain the equipments needed in this experiment.
Write a complete report.

CONCENTRATION AFFECTS RATE OF REACTION

Okay students, now if you use HCl(aq) 3 M, what will happen with the rate of reaction when you compare this with the same mass of marble chips in HCl(aq) 1 M? Which one is faster? Explain the reason.
Is that because of the more H+ ions in the solution? What do the H+ ions act during the reaction?
After explaining this process, please think about another factor affecting rate of reaction by using this reaction.

PLANNING AN EXPERIMENT

This picture ilustrates the reaction between marble chips, CaCO3(s) and an acid, for example HCl(aq). The big red circles are acid molecules and the small red circles are H+(aq) and Cl-(aq).
1. Write down the molecular equation of this reaction. Write a complete equation.
2. Write the ionic equation.
3. If you double or triple the concentration of acid, what will happen with the reaction? Is the process will faster of slower than the first?
4. Make a plan to observe the rate of reaction if you manipulate the concentration of the acid.

NAMING COVALENT COMPOUNDS

Binary Compounds of Two Nonmetals
Given Formula, Write the Name
We will discuss how to name binary compounds from the formula when two nonmetals are involved.
In this compound, you do not even need to know the charges, because it is a covalent compound, no metal here. Use Greek number for prefix. Here are the first ten:
one mono- six hexa-
two di- seven hepta-
three tri- eight octa-
four tetra- nine nona-
five penta- ten decen a-
1. N2O Dinitrogen oxide
2. Cl2O7 Dichlor heptoxide
Given Name, Write the Formula
1. Nitrogen dioxide, NO2
2. Carbon tetrachloride, CCl4

NAMING IONIC COMPOUNDS

In naming ionic compounds, there are some rules. The first rule is proposed for ionic compounds which have a single cation and a single anion, so this compound consists of 2 different elements, metal and non metal. This compound can be grouped as a binary ionic compound. There is a different binary compound, i.e. a covalent compound.
Binary Compounds of Cations with a single charge.
Given Formula, Write the Name
In your textbook there is a table contains list of cations and anions.
1. Na+ and Cl- forms NaCl, sodium chloride
2. Na+ and O2- forms Na2O, sodium oxide
3. Al3+ and F- forms AlF3, aluminium fluoride
Please remember that all elements involved in the compounds have ONLY ONE charge. It includes both the cation and the anion involved in the formula.
The order for naming a binary compound is first the cation, then the anion.
Use the name of cation with a fixed charge directly from the periodic table.
The name of the anion will be made from the root of the element's name plus the suffix "-ide."
Given Name, Write the Formula
The order for writing a formula is first the cation, then the anion.
You have to know the charges of each cation and anion.
The sum of the positive charge and the sum of the negative charges must add up to zero, because compound is neutral.
You may adjust the subscripts to get a total charge of zero. Don't change the charge of each ion.
1. Potassium sulfide, K2S
2. Barium bromide, BaBr2
Binary Compounds of Cations with Variable Charges
Given Formula, Write the Name
The cations involved at least have 2 charges. In your texbook there is a list of cations with variable charges. For example : Cu +1 and +2; Fe +2 and +3; Hg +1 and +2; Pb +2 and +4; Sn +2 and +4; Au +1 and +3.
1. FeCl2, Iron(II) chloride
2. Cu2O, Copper(I) oxide
Polyatomic Compounds
There are polyatomic cations and anions. This compound consists of monoatomic cation and polyatomic anion or polyatomic cation and monoatomic anion or both cation and anion are polyatomic.
1. K2SO4, Potassium sulphate
2. (NH4)2S, Ammonium sulfide
3. NH4NO2 Ammonium nitrite

RATE OF REACTION QUIZ Part II

1. For 2NO + O2 --> 2NO2 , initial rate data are:
[NO] 0.010 M; 0.010 M; 0.030 M
[O2 ] 0.010 M; 0.020 M; 0.020 M
rate 2.5; 5.0; 45.0 mM/sec
The rate law is Rate = k[O2 ]y and ....
a. x = 1 y = 2
b. x = 2 y = 1
c. x = 1 y = 1
d. x = 2 y = 2
e. none of these
2. A and B are mixed and the reaction is timed until a color change occurs. The data are:
[A] 0.100 M; 0.050 M; 0.100M
[B] 0.140 M; 0.140 M; 0.070M
time 25 sec; 50 sec; 100 sec
The order of the reaction in terms of [A] is ....
a. zero
b. second
c. half
d. first
e. none of these
3. If a reaction is first order with a rate constant of 5.48 x 10-2 sec-1, how long is required for 3/4 of the initial concentration of reactant to be used up?
a. 25.3 sec
b. 36.5 sec
c. 6.3 sec
d. 18.2 sec
e. none of these
4. The rate of a specific chemical reaction is independent of the concentrations of the reactants. Thus the reaction is ....
a. first order
b. second order
c. exothermic
d. catalyzed
e. none of these
5. The following rate data were obtained at 20oC for the reaction of hemoglobin (Hb) carbon monoxide reaction. What is the rate-law expression for this reaction:
4 Hb + 3 CO --> Hb4(CO)3
Exp. [Hb] mol/L; [CO] mol/L; Rate of disappearance of Hb (M/sec)
1 - 3.36 x 10-6; 1.00 x 10-6; 9.41 x 105
2 - 6.72 x 10-6; 1.00 x 10-6; 1.88 x 106
3 - 6.72 x 10-6; 2.00 x 10-6; 3.76 x 106
a. rate = k[Hb]4[CO]3
b. rate = k[Hb]2 [CO]2
c. rate = k[Hb] [CO]
d. rate = k[Hb]
e. rate = k[Hb] [CO]2
6. The following rate data were obtained at 25oC for the indicated reaction. What is the rate-law expression for the reaction:
A + B --> 2 C?
Exp. [A] mol/L; [B] mol/L; te of formation of C (M/min)
1 - 0; 10; 0 x 10-4
2 - 0; 30; 2 x 10-2
3 - 0; 30; 6 x 10-3
4 - 0; 20; 4 x 10-3
a. rate = k[A] [B]
b. rate = k[A] [B]2
c. rate = k[A]2 [B]2
d. rate = k[B]
e. rate = k[A]2[B]
7. The following rate data were obtained at 25oC for the indicated reaction. What is the rate-law expression for the reaction:
2 A + B --> ?
Exp [A] mol/L; [B] mol/L; Rate of formation of C (M/min)
1 - 0.10; 0.10; 2.0 x 10-4
2 - 0.20; 0.10; 8.0 x 10-4
3 - 0.40; 0.20; 2.6 x 10-2
a. rate = k[A]2 [B]2
b. rate = k[A] [B]
c. rate = k[A]2[B]3
d. rate = k[A] [B]2
e. rate = k[A]2[B]
8. The following rate data were obtained at 25oC for the indicated reaction. What is the rate-law expression for the reaction:
2 A + B --> 3 C?
Exp. [A] mol/L; [B] mol/L; Rate of formation of C (M/min)
1 - 0.10; 0.10; 4.0 x 10-4
2 - 0.30; 0.30; 1.2 x 10-3
3 - 0.10; 0.30; 4.0 x 10-4
4 - 0.20; 0.40; 8.0 x 10-4
a. rate = k[A]
b. rate = k[A] [B]
c. rate = k[A] [B]2
d. rate = k[A]2[B]
e. rate = k[B]
9. The decomposition of N2O5(g) à NO2(g) + NO3(g) proceeds as a first order reaction with a half-life of 30.0 seconds at a certain temperature. If the initial concentration [N2O5]0 = 0.400 M, what is the concentration after 120 seconds?
a. 0.000 M
b. 0.100 M
c. 0.025 M
d. 0.200 M
e. 0.050 M
10. What is the rate constant of the reaction in the above Problem ?
a. 2.31 x 10-2 s-1
b. 2.31 x 10-1 s-1
c. 20.7 s-1
d. 30.0 s-1
e. 43.3 s-1

RATE OF REACTION QUIZ Part I

1. The rate of a reaction ….
a. is independent of temperature
b. decreases as the reaction proceeds
c. is independent of concentration
d. is not affected by catalysts

2. Choose the INCORRECT answer. The rate of a chemical reaction ....
a. usually is increased when the concentration of one of the reactants is increased
b. is dependent on temperature
c. may be inhibited sometimes by certain catalytic agents
d. will be very rapid if the activation energy is large

3. The rate of a reaction at any given point in time (the instantaneous rate) is equal to ….
a. the product of k and t
b. the sum of k and t
c. the negative slope of the line tangent to the reaction curve of concentration vs t
d. the absolute value of the slope of the line tangent to the reaction curve of concentration vs t
4. Beaker A contains a 1-grams piece of zinc and beaker B contains 1 gram of powdered zinc. If 100 milliliters of 0.1 M HCl is added to each of the beakers, how does the rate of reaction in beaker A compare to the rate of reaction in beaker B?
a. The rate in A is greater due to the smaller surface area of the zinc.
b. The rate is A is greater due to the greater surface area of the zinc.
c. The rate in B is greater due to the smaller surface area of the zinc.
d. The rate is B is greater due to the greater surface area of the zinc.
5. At which temperature does an aqueous solution of LiCl have the highest average kinetic energy?
a. 100 C
b. 150 C
c. 200 C
d. 273 K
e. 373 K
6. A variable that has NO EFFECT on reaction rate is ....
a. energy of activation
b. temperature
c. catalyst
d. concentration
e. none of these
7. Which of the following lowers the activation energy of a reaction?
a. adding reactants
b. lowering the temperature
c. removing products
d. adding a catalyst
e. raising the temperature
8. A catalyst ....
a. takes part in a reaction and speeds it up
b. appears in the rate equation of a chemical reaction
c. provides an alternate reaction pathway
d. raises the activation energy of a reaction
e. none of the above
9. A catalyst will affect the rate of the forward reaction by changing the ....
a. activation energy
b. heat of reaction
c. heat of formation
d. potential energy of the products

10. A catalyst alters the rate of a chemical reaction by ....
a. always providing a surface on which molecules react
b. changing the products formed in the reaction
c. inducing an alternate pathway for the reaction with generally lower activation energy
d. changing the frequency of collisions between molecules

11. The catalytic converter in an automobile uses NiO and Pt metal to speed the combustion of CO to CO2. This is an example of ....
a. homogeneous catalysis
b. heterogeneous catalysis
c. acid hydrolysis
d. enzyme catalysis
12. If the rate of a reaction is determined at the instant a reaction begins
a. the reverse reaction can be ignored
b. the products will not show up in the rate law
c. only the reactant concentrations will affect the rate of the reaction at the specified conditions
d. only the forward reaction needs to be considered
e. all of the above

13. The rate law of a reaction (choose 2)
a. provides information about the reaction mechanism
b. shows the intermediates of a reaction
c. may be used to identify the rate determining step of a complex reaction
d. will aid in writing the balanced chemical equation for the reaction

14. If the concentration of a reactant is doubled and the rate of the reaction doubles, with all other factors which would affect the rate of the reaction held constant, the order of the reactant is ....
a. zero
b. first
c. second
d. third
e. forth
15. If the concentration of a reactant is doubled and the rate of the reaction quadruples, with all other factors which would affect the rate of the reaction held constant, the order of the reactant is ....
a. zero
b. first
c. second
d. third
e. forth
16. If the concentration of a reactant is doubled and the rate of the reaction does not change, with all other factors which would affect the rate of the reaction held constant, the order of the reactant is ....
a. Zero
b. First
c. Second
d. third
e. forth
17. Which of the following is the rate law (differential) of the reaction aA --> B, if reactant A is zero order?
a. Rate = k
b. Rate = k[A]
c. Rate = [A]
d. Rate = k[A]2
e. Rate = [A]2
18. Which of the following is the rate law (differential) of the reaction aA --> B, if reactant A is second order?
a. Rate = k
b. Rate = k[A]
c. Rate = [A]
d. Rate = k[A]2
e. Rate = [A]2
19. What is the overall order for the reaction whose rate law is Rate = k[A]2[B]?
a. 0
b. 1
c. 2
d. 3
e. 4
20. If a reaction has a rate equation of rate = k[A][B][C] then it is ....
a. second order
b. first order
c. third order
d. zero order
e. cannot be determined
21. Zero-order reactions ....
a. often involve catalysts
b. often occur on a metal (e.g. platinum, palladium) surface
c. are unaffected by changes in the concentrations of the reactants
d. have their rate determined by the active sites on the enzymes or metal surface
e. all of the above

STOICHIOMETRY QUIZ Part III

1. Determine the mass (g) of solute required to form 275 mL of a 0.5 M KClO4 solution. (Ar K = 39, O = 16, Cl = 35.5).
a. 19.6
b. 12.2
c. 8.6
d. 4.2
e. 1.97
2. For reasons of taste, the maximum chloride ion content of domestic water supplies has been set at 0.025 g/L. What is the maximum content of chloride ion in moles per liter? (Ar Cl = 35.5).
a. 9.0 x 10-2
b. 7.1 x 10-4
c. 7.1 x 10-2
d. 9.0 x 10-3
e. 5.0 x 10-4
3. If some water are added to 10 cm3 of hydrochoric acid 2M and forms 100 cm3 of solution, the new molarity of the acid is ….
a. 0,1 mol dm-3
b. 0,2 mol dm-3
c. 0,3 mol dm-3
d. 0,4 mol dm-3
e. 0,5 mol dm-3
4. Fluoxymesterone, C20H29FO3, is an anabolic steroid. A solution is prepared by dissolving 10.0 mg of the steroid in 500.0 mL of water. A 1.00 mL portion of this solution is diluted to a final volume of 1.00 L. What is the resulting molarity? (Ar C = 12, O = 16, F = 19, H = 1).
a. 1.19 x 10-7
b. 5.94 x 10-11
c. 5.94 x 10-8
d. 2.38 x 10-11
e. 1.19 x 19-10
5. A solution is prepared by dissolving 516.5 mg of oxalic acid (C2H2O4) to make 100.0 mL of solution. A 10.00 mL portion is then diluted to 250.0 mL. What is the molarity of the final solution? (Ar C = 12, H = 1, O = 16).
a. 5.7 x 10-2
b. 2.3
c. 2.3 x 10-3
d. 5.7 x 10-2
e. 5.7
6. How many moles of lead chromate, PbCrO4, the pigment "chrome yellow", often used by artists, can be produced by addition of excess sodium chromate, Na2CrO4, to 25 mL of a 0.493 M solution of lead(II) nitrate, Pb(NO3)2? (Ar Pb = 207, Cr = 52, O = 16, Na = 23).
Pb(NO3)2+Na2CrO4 --> 2 NaNO3+PbCrO4
a. 0.018
b. 0.024
c. 0.006
d. 0.012
e. 0.015
7. How many moles of calcium carbonate, CaCO3, are required to react with the sulfuric acid in 375.4 mL of a 0.9734 M solution of H2SO4? (Ar Ca = 40, C = 12, O = 16).
CaCO3(s)+H2SO4(aq) --> CaSO4(s)+H2O+CO2
a. 0.1829
b. 0.1256
c. 0.7132
d. 0.3654
e. 0.8238
8. What mass of the active metal magnesium is required to react exactly with the hydrochloric acid in a 125.0 mL sample of a 0.2110 M solution of HCl? (Ar Mg = 24).
Mg(s) + 2 HCl(aq) --> MgCl2(aq) + H2(g)
a. 0.27
b. 0.16
c. 0.21
d. 0.32
e. 0.29
9. What volume, in mL, of 0.265 M HBr will react completely with 0.155 g of zinc? (Ar Zn = 65.4, Br = 80, H = 1).
Zn + 2 HBr --> ZnBr2 + H2
a. 15
b. 8.9
c. 7.3
d. 18
e. 4.5
10. What volume of 0.0916 M BaCl2 will react completely with 0.475 g of Na2SO4? (Ar Ba = 137, S = 32, Cl = 35.5, Na = 23, O = 16).
BaCl2 + Na2SO4 --> BaSO4 + 2 NaCl
a. 28.8
b. 31.2
c. 33.4
d. 36.5
e. 41.6
11. Calcium carbonate solid is added to a solution of hydrochloric acid. The molarity of acid is 2,0 M and the mass of calcium carbonate (Mr = 100) is 10 grams. The volume of HCl(aq) which needed in this reaction is ….
a. 25 mL
b. 100 mL
c. 50 mL
d. 150 mL
e. 75 mL

STOICHIOMETRY QUIZ Part II

1. A solution of sodium hydroxide is prepared by using a sodium hydroxide solid. If 500 cm3 water are added to 4 grams of sodium hydroxide solid (Mr = 40), the molarity of its solution is ….
a. 0,01 mol dm-3
b. 0,02 mol dm-3
c. 0,05 mol dm-3
d. 0,10 mol dm-3
e. 0,20 mol dm-3
2. Calculate the molarity of a solution of 0.0716 g of KMnO4 in 2.50 mL of solution. (Ar K = 39, Mn = 55, O = 16).
a. 0.522
b. 0.452
c. 0.362
d. 0,181
e. 0,125
3. What is the molarity of 0.195 g of cholesterol (C27H46O) in 0.10 L of blood serum? (Ar C = 12, H = 1, O = 16).
a. 5.0 x 10-2
b. 5.0 x 10-3
c. 2.0 x 10-3
d. 5.0 x 10-4
e. 2.0 x 10-2
4. Calculate the molarity of a solution of 13.3 g of MgI2 in 0.20 L of solution.(Ar Mg = 24, I = 127).
a. 0.18
b. 0.48
c. 0.96
d. 0.24
e. 1.2
5. Hydrogen peroxide, H2O2 is colorless liquid. Dilute aqueous solutions are used as a bleach. Analysis of a solution shows that it contains 0,90 mol H2O2 in 1,0 L of solution. The mass of H2O2 in 0,5 L of solution is …. (Ar H = 1; Ar O = 16)
a. 0,45 x 17 g
b. 0,90 x 17 g
c. 1,80 x 17 g
d. 0,45 x 34 g
e. 1,80 x 34 g
6. Determine the number of moles of solute present in 25 mL of 0.188 M H2O2. (Ar O = 16, H = 1).
a. 3.5 x 10-3
b. 4.7 x 10-3
c. 5.3 x 10-3
d. 4.7 x 10-2
e. 3.5 x 10-2
7. Determine the number of moles of solute present in 275 mL of 0.5151 M KClO4. (Ar: Cl = 35.5, O = 16, K = 39).
a. 0.189
b. 0.142
c. 0.212
d. 0.0922
e. 0.112
8. Determine the number of moles of solute present in 416 mL of 3.75 M HBr solution. (Ar Br = 80, H = 1).
a. 1.71
b. 1.56
c. 1.98
d. 1.23
e. 1.89
9. Determine the mass (g) of solute required to form 250.0 mL of a 0.250 M NaCN solution. (Ar Na = 23, C = 12, N = 14).
a. 2.91
b. 2.72
c. 3.21
d. 2.51
e. 3.06
10. Determine the mass (g) of solute required to form 275 mL of a 0.42 M KClO3 solution. (Ar K = 39, O = 16, Cl = 35.5).
a. 19.6
b. 12.2
c. 1.97
d. 4.21
e. 14.3

STOICHIOMETRY QUIZ Part I

1. Sodium is a soft, reactive metal that instantly reacts with water to give hydrogen gas and a solution of sodium hydroxide. Ar Na = 23; Ar H = 1; Ar O = 16. The mass of sodium which needed to give 2,24 L at STP is ….
a. 1,2 g
b. 2,3 g
c. 4,6 g
d. 5,7 g
e. 8,0 g
2. A solution of sodium carbonate is added to a solution of hydrochloric acid. If the mass of sodium carbonate is 2,12 grams (Mr = 106), the volume of the gas produced at STP is ….
a. 112 cm3
b. 224 cm3
c. 336 cm3
d. 448 cm3
e. 560 cm3
3. A 5,72 g of Sodium carbonate deka hydrate (Mr = 286) is heated to form sodium carbonate anhydrate (Mr = 106). The correct statement about this reaction is ….
a. the type of reaction is cristalization
b. Na2CO3.10H2O(s) à Na2CO3(s) + 10H2O(g)
c. the amount of reactant is 0,01 mol
d. the salt produced is 0,01 mol
e. the mass of the product is 1,06 g
4. Calcium reacts with water according to the following reaction. At STP, what volume (L) of hydrogen would be produced by the reaction of 1.2 grams of calcium? (Ar: Ca = 40, H = 1, O = 16).
Ca(s) + 2 H2O(l) --> Ca(OH)2(aq) + H2(g)
a. 335
b. 440
c. 540
d. 671
e. 585
5. A commercial drain cleaner results in the following reaction in a clogged drain. What volume of H2 (L) at STP is produced when 4.25 g of aluminum reacts? (Ar: Al = 27, Na = 23, O = 16, H = 1).
2 NaOH(aq) + 2 Al(s) + 6 H2O
2 NaAl(OH)4(aq) + 3 H2(g)
a. 6.01
b. 2.44
c. 4.56
d. 5.29
e. 3.33
6. Pure tungsten can be prepared by the following reaction. What volume (L) of H2 at 0.980 atm and 20oC is required to react with 25.2 g of WO3? (Ar: W = 184, H = 1, O = 16).
3 H2(g) + WO3(s) --> W(s) + 3 H2O(g)
a. 7.20
b. 2.67
c. 9.00
d. 8.00
e. 4.50
7. A 3.040 g sample of impure calcium phosphide reacts with water to give 685 mL of PH3 at 20oC and 745 mm Hg. What is the % Ca3P2? (Ar: Ca = 40, P = 31, H = 1, O = 16).
Ca3P2(s) + 6 H2O(l) --> 3Ca(OH)2(s) + 2 PH3(g)
a. 83.9
b. 85.9
c. 76.2
d. 88.2
e. 80.8
8. An alloy consists of 5.0% Cu and 95.0% Al. Aluminum reacts with HCl but copper does not. What mass of alloy is required to produce 1.96 g of hydrogen gas? (Ar Al = 27, H = 1, Cl = 35.5).
2 Al + 6 HCl --> 2 AlCl3 + 3 H2
a. 17.5
b.18.4
c. 23.0
d. 1
e. 27.6
9. The mass of H2 produced by reaction of 1.60 g Fe and 2.00 g HCl is 0.0505 g. What is the percent yield? (Ar Fe = 56, Cl = 35.5, H = 1).
Fe + 2 HCl --> FeCl2 + H2
a. 89
b. 90
c. 92
d. 91
e. 90
10. The mass of H2 produced by reaction of 1.80 g Al and 6.00 g H2SO4 is 0.112 g. What is the percent yield? (Ar Al = 27, S = 32, O = 16, H = 1).
2 Al + 3 H2SO4 --> Al2(SO4)3 + 3 H2
a. 92.4
b. 93.4
c. 93.0
d. 90.8
e. 94.5

CHEMICAL FORMULA QUIZ Part II

1. When 0.880 g of an organic compound containing carbon, hydrogen and oxygen is burned completely in oxygen, 1.760 g of CO2 and 0.720 g H2O are produced. What is the empirical formula of the compound? (Ar: C = 12, H = 1, O = 16).
a. C2H4O
b. C3H6O2
c. CHO
d. C2H2O
e. C3H6O4
2. A 0.765 g sample of an organic compound containing only carbon, hydrogen and oxygen was burned completely in air to produce 1.10 g of CO2 and 0.564 g of H2O. What is the empirical formula of the compound? (Ar: C = 12.01, H = 1.008, O = 16.00).
a. C2H5O2
b. C2H5O
c. C2H4O
d. C2H3O
e. C2H6O
3. A compound used to produce nylon contains only carbon, hydrogen and nitrogen. When a 0.4634 g sample is burned completely in oxygen, 1.054 g of CO2 and 0.1437 g of H2O are formed. What is the empirical formula? (Ar: C = 12, H = 1, O = 16, N = 14).
a. C3H5N
b. C3H6N3
c. C3H5N2
d. C3H8N
e. C3H7N2
4. Aziridine contains only carbon, hydrogen and nitrogen. When a 0.4622 g sample is burned completely in oxygen, 0.9673 g of CO2 and 0.3960 g of H2O are formed. What is the empirical formula? (Ar: C = 12.01, H = 1.008, O = 16.00, N = 14.01).
a. C2H3N
b. CHN
c. C3H6N
d. C2H4N
e. C2H4N3
5. A sample of nicotine which contains only carbon, nitrogen and hydrogen is burned in excess oxygen. A 0.234 g sample yielded 0.183 g of H2O and 0.633 g of CO2. What is the empirical formula of nicotine? (Ar: C = 12, H = 1, N = 14, O = 16).
a. C4H7N
b. C4H9N
c. C3H7N2
d. C5H7N
e. C3H5N
6. A sample of nicotine which contains only carbon, nitrogen and hydrogen is burned in excess oxygen. A 0.2340 g sample yielded 0.1826 g of H2O and 0.6329 g of CO2. What is the empirical formula of nicotine? (Ar: C = 12, H = 1, N = 14, O = 16).
a. C4H7N
b. C4H9N
c. C3H7N2
d. C5H7N
e. C3H5N
7. A compound used to fumigate contains only carbon, hydrogen and bromine. When a 7.514 mg sample is burned completely in oxygen, 3.521 mg of CO2 and 1.441 mg of H2O are formed. What is the empirical formula? (Ar: C = 12, H = 1, O = 16, Br = 80).
a. C2H4Br3
b. CH2Br
c. C3H2Br2
d. CHBr
e. C2H4Br

CHEMICAL FORMULA QUIZ Part I

1. An ascorbic acid (a vitamine C) contains only C, H, and O elements. A 3,87 mg sample of ascorbic acid gives 5,80 mg CO2 and 1,58 mg H2O on combustion. The percentage composition of this compound is …. (Ar C = 12; Ar H = 1; Ar O = 16)
a. 30% C, 15% H, and 55% O
b. 40% C, 5% H, and 55% O
c. 50% C, 5% H, and 45% O
d. 55% C, 10% H, and 35% O
e. 60% C, 15% H, and 25% O
2. The molecular formula of a compound is represented by X3Y6. What is the empirical formula of this compound?
a. X3Y
b. X2Y
c. XY2
d. XY3
e. XY
2. Determine the empirical formula of Teflon which is 24.0% C and 76.0% F. (Ar C = 12.01, F = 19.00).
a. CF2
b. CF3
c. CF
d. C2F
e. C2F3
3. Determine the empirical formula of natural rubber which is 88.2% C and 11.8% H. (Ar C = 12.01, H = 1.008).
a. C5H8
b. C2H5
c. C2H7
d. C3H7
e. C3H5
4. Determine the empirical formula of saran which is 24.8% C, 2.1% H and 73.1% Cl. (Ar C = 12.01, H = 1.008, Cl = 35.45).
a. CHCl
b. CH2Cl
c. C2H2Cl
d. CH3Cl
e. C2HCl
5. The empirical formula of a compound which consists of 26% N and 74% O is ….
a. NO
b. NO2
c. N2O
d. N2O3
e. N2O5
6. A semiconductor consists of 25.5% gallium and 74.5% vanadium What is the empirical formula? (Ar Ga = 69.7, V = 50.9).
a. GaV3
b. GaV2
c. GaV4
d. Ga2V5
e. Ga2V3
7. A semiconductor consists of 37.2% aluminum and 62.8% zirconium. What is the empirical formula? (Atomic weights: Al = 27.0, Zr = 91.2).
a. AlZr2
b. AlZr
c. Al2Zr
d. Al2Zr3
e. Al3Zr2
8. A semiconductor consists of 47.6% silver and 52.4% tin What is the empirical formula? (Ar Ag = 107.9, Sn = 118.7).
a. Ag2Sn
b. AgSn2
c. AgSn
d. Ag2Sn3
e. Ag3Sn2
9. The mineral forsterite contains 34.5% Mg, 20.0% Si and 45.5% O. What is the empirical formula? (Ar Mg = 24.3, Si = 28.1, O = 16.00).
a. Mg2SiO3
b. Mg2SiO2
c. MgSiO4
d. MgSiO3
e. Mg2SiO4
10. Benzoic acid is a white, crystalline powder used as a food preservative. The compound contains 68,8% C, 5,0% H, and 26,2% O, by mass. Ar C = 12; H = 1; O = 16. The empirical formula of benzoic acid is ….
a. C2H3O2
b. C3H6O2
c. C5H5O
d. C6H5O2
e. C7H6O2
11. The molecular formula of a compound which has an empirical formula of CH3 and a molar mass of 30 g mol-1 is ….
a. CH3
b. CH6
c. C2H3
d. C2H6
e. C3H9

MOL CONCEPT QUIZ Part II

1. What is the total number of moles of sulfur atoms in 1 mole of Fe2(SO4)3?
a. 1
b. 3
c. 7
d. 15
e. 17
2. What is the total number of moles of all atoms in 1 mole of (NH4)2SO4?
a. 1
b. 3
c. 7
d. 15
e. 17
3. Which sample contains a total of 6.0 x 1023 atoms?
a. 23 g Na (Ar 23)
b. 24 g Ca (Ar 40)
c. 42 g K (Ar 39)
d. 44 g F (Ar 19)
e. 78 g Cl (Ar 35.5)
4. The molar mass of carbon is 12 g/mol. If the Avogadro’s numbers are 6 x 1023, the mass in grams of a carbon atom is ...
a. 2x10 -23
b. 1,2x10 -23
c. 10 -23
d. 1,2x10 23
e. 2x10 23
5. The molar mass of oxygen is 16 g/mol. If the Avogadro’s numbers are 6 x 1023, the mass in grams of an oxygen atom is
a. 2x10 -23
b. 2,7x10 -23
c. 10 -23
d. 1,2x10 23
e. 2x10 23
6. The formula of an acid is H2XO6. The mass of 0.0102 moles of the acid is 2.301 g. What is the atomic weight of X? (Ar O = 16.00, H = 1.008).
a. 128
b. 79.0
c. 35.5
d. 28.1
e. 11.5
7. The formula of an acid is HXO2. The mass of 0.0242 moles of the acid is 1.657 g. What is the atomic weight of X? (Ar O = 16.00, H = 1.008).
a. 35.5
b. 28.1
c. 128
d. 19.0
e. 79.9
8. Vitamin B2 which contains carbon, hydrogen, nitrogen and oxygen is 14.9% nitrogen by mass. There are four nitrogen atoms per molecule. What is the molecular weight of vitamin B2? (Ar C = 12, O = 16, H = 1, N = 14).
a. 1504
b. 376
c. 352
d. 312
e. 94
9. Cocaine, an addictive drug, is 4.62% nitrogen. There is one nitrogen atoms per molecule. What is the molecular weight of cocaine? (Ar N = 14.00).
a. 312
b. 308
c. 303
d. 300
e. 295
10. Hydrogen cyanide, HCN is a volatile, colorless liquid with the odor of certain fruit pits. The compound is highly poisonous. The number of molecules in 54 mg HCN (Mr = 54), the everage toxic dose are ….
a. 6,02 x 1020
b. 1023
c. 6,02 x 1023
d. 542 x 6,02 x 1020
e. 542 x 6,02 x 1023
11. Barium chloride, BaCl2 is an ionic compound. If the Avogadro’s number = 6,0 x 1023, the number of cations and anions in 2,08 g BaCl2 (Ar Ba = 137; Ar Cl = 35,5) are ….
a. 1,2 x 1021
b. 6,0 x 1021
c. 1,2 x 1022
d. 1,8 x 1022
e. 1,2 x 1023
12. BaSO4 is an ionic compound. If the Avogadro’s number = 6,0 x 1023, the number of cations and anions in 2,33 g BaCl2 (Ar Ba = 137; Ar S = 32, Ar O = 16) are ….
a. 1,2 x 1021
b. 6,0 x 1021
c. 1,2 x 1022
d. 1,8 x 1022
e. 1,2 x 1023
13. The number of atoms in iron is 1,2 x 1023. The number of mole in iron is ….
a. 0,1
b. 0,2
c. 0,4
d. 0,6
e. 0,8
14. The number of molecules in water is 1,2 x 1022. The mass of water in grams is …. (Ar H = 1; Ar O = 16)
a. 0,1 .
b. 0,2
c. 0,4
d. 0,6
e. 0,8
15. The number of molecules in water is 1,2 x 1022. The number of atoms in water is ….
a. 1,2 x 1022
b. 2,4 x 1022
c. 3,6 x 1022
d. 1,2 x 1023
e. 2,4 x 1023
16. Equal volumes of CO2 gas and a fluorocarbon gas weigh 1.00 and 3.41 grams under the same experimental conditions. Which of the following is the unknown gas? (Ar: C = 12.01, F = 19.00).
a. C3F4
b. C2F6
c. C3F6
d. C2F4
e. CF4
17. Nitric acid, HNO3 is a colorless, corrosive liquid used in the manufacture of nitrogen fertilizers and explosives. In an experiment, a 6,30 g sample of nitric acid was poured into a beaker. The number of mole of HNO3 (Mr = 63) in the sample of nitric acid are ….
a. 0,01
b. 0,05
c. 0,10
d. 1,00
e. 10,0

MOL CONCEPT QUIZ Part I

1. The molecule mass relative of H2SO4 is …. (Ar H= 1 Ar S = 32; and Ar O = 16)
a. 89
b. 98
c. 108
d. 112
e. 14
2. The formula mass relative of copper(II) sulfate pentahydrate is …. (Ar Cu = 63,5; S = 32; O = 16; and H = 1)
a. 159,5
b. 249,5
c. 255,5
d. 313,0
e. 403,0
3. The formula mass relative of barium hydroxide octahydrate is …. (Ar Ba = a; Ar O = b; and Ar H = c)
a. 8 (a + 3b+ 4c)
b. (a + 2b + 2c) (16c + 8b)
c. (a + 2b + 2c) 8 (2c + b)
d. (a + 2b + 2c) + 8 (b + 2c)
e. (a + 2b + 2c) (2c + b)
4. The molar mass of potassium is 39 g/mol. If the Avogadro’s numbers are 6 x 1023, the mass in grams of a potassium atom is ….
a. 6,5x10 -23
b. 3,9x10 -23
c. 1,3x10 -23
d. 3,9x10 23
e. 6,5x10 23
5. What volume will 2.80 g of N2 occupy at STP? (Ar N = 14).
a. 2.23 L
b. 5.6 L
c. 11.2 L
d. 22.4 L
e. 44.8 L
6. Hydrogen peroxide, H2O2 is colorless liquid. Analysis of a solution shows that it contains 0,90 mol H2O2 in 1,0 L of solution. The mass of H2O2 in 2,0 L of solution is …. (Ar H = 1; Ar O = 16)
a. 0,45 x 17 g
b. 0,90 x 17 g
c. 1,80 x 17 g
d. 0,45 x 34 g
e. 1,80 x 34 g
7. Nitric acid, HNO3 is a colorless and corrosive liquid. In an experiment, a 3,15 g sample of this acid was poured into a beaker. The number of moles in 3,15 g sample of HNO3 (Mr = 63) are ….
a. 0,01
b. 0,02
c. 0,05
d. 0.10
e. 0,50
8. Vitamin A is C20H30O. What is the molecular weight of the vitamin?(Ar C = 12, O = 16, H = 1).
a. 270.4
b. 220.4
c. 256.2
d. 286.4
e. 240.2
9. Which of the following organic compounds has the lowest molecular weight? (Ar C = 12.01, N = 14.01, H = 1.008).
a. C7H14
b. C6H10N2
c. C4H8N4
d. C7H11N
e. C5H11N3
10. Silver (Atomic weight 107.87) has two naturally-occurring isotopes with isotopic weights of 106.91 and 108.90470. What is the percentage abundance of the heavier isotope?
a. 47.24
b. 49.05
c. 51.82
d. 50.95
e. 48.16

BASIC LAW OF CHEMISTRY QUIZ

1. According to the Lavoisier’s Law, if a 12 grams of Mg(s) reacts with a 10 g of oxygen(g), the product formed is 20 g MgO(s) and there is an excess of oxygen gas. The wrong answer is ….
a. after reaction the mass = 22 grams
b. not all of the oxygen gas reacts with Mg
c. the excess mass of oxygen gas is 2 grams
d. the mass of product = the mass of reactants
e. all magnesium reacts to form magnesium oxide
2. Sodium(s) reacts with an oxygen gas in the air, forms an oxide. If the mass of sodium is 2,3 g and the mass of the oxide is 3,1 g, the mass of oxygen gas is ….
a. less than 0,8 g
b. 0,8 g
c. more than 0,8 g
d. 1,6 g
e. more than 1,6 g
3. Potassium(s) reacts with an oxygen gas in the air, forms a metal oxide(s). If the mass of potassium is 3,9 g and the mass of the oxide is 4,7 g, the correct answer is ….
a. m O2(g) = 0,8 g
b. m K2O(s) < m K(s)
c. m K(s) = m K2O(s)
d. the mass of reactants > 4,7 g
e. the mass of product < the mass of reactants
4. If a 6,5 grams of Zn(s) reacts with a 2 grams of O2(g), the compound formed is 8,1 grams ZnO(s) and there is an excess of oxygen gas. The wrong answer is
a. the limiting reactant is zinc
b. all zinc reacts to form zinc oxide
c. after reaction the mass = 8,1 grams
d. not all of the oxygen gas reacts with zinc
e. the excess mass of oxygen gas is 0,4 grams
5. Cu(s) + S(s) à CuS(s) The correct answer which relates with the graph is ..
a. the mass ratio of Cu : S = 1 : 2
b. the mass of Cu = the mass of S
c. if m Cu = 10 g, m S = 20 g
d. the mass’ ratio of both elements can change
e. if m S = 6 g, m Cu = 12 g
6. Cu(s) + S(s) --> CuS(s) The mass’ ratio of Cu : S in CuS = 2 : 1. The wrong answer about this information is ….
a. if the mass of Cu = 4 g, the mass of S = 2 g
b. if m S = 20 g, m CuS = 60 g
c. the mass’ ratio of both elements can change
d. this reaction proves the Proust’s Law
e. the mass before and after reaction are the same
7. Carbon and oxygen can form two different compounds, CO and CO2. The mass of CO = 2,8 g and the mass of CO2 = 4,4 g. If the mass of C in both compounds is 1,2 g, the wrong answer is ….
a. m O in CO > m O in CO2
b. m O in CO : O in CO2 = 1 : 2
c. if m C = 2,4 g; m O in CO = 3,2 g
d. the mass of O in first compound is 1,6 g
e. the mass of O in the second compound is 3,2 g
8. There are two compounds, NO and NO2. The mass of NO = 30 g and the mass of NO2 = 46 g. If the mass of N in both compounds is 14 g, the wrong answer is ….
a. the mass of O in first compound is 16 g
b. the mass of O in the second compound is 32 g
c. the mass’ ratio of O in NO : O in NO2 = 2 : 1
d. if the mass of N = 7 g, m O in NO = 8 g
e. if the mass of N = 28 g, m O in NO : O in NO2 = 1 : 2
9. In an industrial process, hydrogen chloride, HCl is prepared by burning hydrogen gas in atmosphere of chlorine. If a 10 dm3 of HCl(g) is produced, the total volume of H2(g) and Cl2(g) are ….
a. 5 dm3
b. 10 dm3
c. 20 dm3
d. 30 dm3
e. 40 dm3
10. If 150 cm3 of a hydrogen gas, H2 is added to 200 cm3 of a nitrogen gas, N2 forms ammonia gas,NH3 (P,T). The volume of ammonia is ….
a. 50 cm3
b. 100 cm3
c. 150 cm3
d. 200 cm3
e. 250 cm3
11. If 100 cm3 of a hydrogen gas is added to 200 cm3 of a chlorine gas, forms hydrogen chloride gas (P,T). The volume of the product is ….
a. 100 cm3
b. 200 cm3
c. 300 cm3
d. 400 cm3
e. 500 cm3
12. Two dm3 of CxHy gas burns in 5 dm3 oxygen gas. If there is 4 dm3 CO2(g), the chemical formula of CxHy is ….
a. C2H2
b. C2H4
c. C2H6
d. C3H3
e. C3H6

CHEMICAL EQUATION QUIZ Part II

1. Methane gas is burnt as a source of energy for cooking and heating. One molecule of methane gas and 2 molecules of oxygen gas react to form 1 molecule of carbon dioxide gas and 2 molecules of water. The correct equation is ….
a. CH4 + O2 --> CO2 + H2O
b. CH4 + 2O2 --> CO2 + 2H2O
c. CH4(g) + O2(g) --> CO2(g) + H2O(g)
d. CH4(g) + 2O2(g) --> CO2(g) + 2H2O(g)
e. CH4(g) + 2O2(g) --> CO2(g) + 2H2O(l)
2. Solid calcium carbonate is added to a solution of nitric acid to form carbon dioxide gas. The correct balanced equation is ….
a. CaCO3(s) + HNO2(aq) --> Ca(NO3)2(aq) + H2O(l) + CO2(g)
b. CaCO3(s) + 2HNO2(aq) --> Ca(NO3)2(aq) + H2O(l) + CO2(g)
c. CaCO3(s) + HNO3(aq) --> Ca(NO3)2(aq) + H2O(l) + CO2(g)
d. CaCO3(s) + 2HNO3(aq) --> Ca(NO3)2(aq) + H2(l) + CO2(g)
e. CaCO3(s) + 2HNO3(aq) --> Ca(NO3)2(aq) + H2O(l) + CO2(g)
3. Aluminium is added to a solution of hydrochloric acid to form a solution of alminium chloride and hydrogen gas. The correct balanced equation is ….
a. Al(s) + HCl(aq) --> AlCl(aq) + H(g)
b. Al(s)+2HCl(aq) --> AlCl2(aq)+H2(g)
c. 2Al(s)+6HCl(aq) --> 2AlCl3(aq)+ 3H2(g) V
d. Al2(s)+6HCl(aq) --> 2AlCl3(aq) + 3H2(g)
e. 2Al(s) + 6HCl(aq) --> 2AlCl3(aq) + 6H(g)
4. If an acid is added to a base and the reaction is heated, the compound formed is called ….
a. non-acid
b. non-base
c. salt
d. water
e. ionic compound
5. Iron is added to hydrochloric acid, form salt and a gas. The gas is ….
a. Oxygen
b. hydrogen
c. iron
d. chlorine
e. hydrogen chloride
6. Propane gas, C3H8 burns fully in oxygen gas. The ratio of molecules of propane, oxygen, carbon dioxide, and water are
a. 1, 5, 3, 4
b. 1, 4, 3, 5
c. 1, 3, 4, 5
d. 2, 3, 3, 5
e. 2, 5, 6, 8
7. Butane gas, C4H10 is also burnt as a source of energy. One molecule of butane gas reacts with oxygen gas to form carbon dioxide gas and water. The correct number of carbon dioxide molecules and water molecules are ….
a. 2 and 3
b. 2 and 5
c. 4 and 3
d. 4 and 5
e. 4 and 10
8. Pentane liquid, C5H12 burns fully in oxygen gas. The ratio of molecules of pentane, oxygen, carbon dioxide, and water are ….
a. 1, 11, 5, 6
b. 1, 8, 5, 6
c. 1, 5, 3, 4
d. 2, 5, 3, 5
e. 2, 10, 6, 8
9. Fossil fuels usually contain traces of sulfur. The poisonous gas formed when this fuel burns is ….
a. acid
b. sulfur
c. sulfur dioxide
d. sulfur trioxide
e. sulfurous acid
10. Propane, like methane, is a hydrocarbon which can be used as a fuel. It is sold as ‘bottled gas’, for use where there is no mains gas supply. When propane burns with sufficient oxygen, the products formed are ….
a. oxygen and water
b. oxygen and carbon dioxide
c. water and carbon dioxide
d. carbon dioxide and carbon monoxide
e. carbon monoxide and water

CHEMICAL EQUATION QUIZ Part I

1. Heated calcium burns in chlorine to form salt. The correct word equation is ….
calcium + chlorine --> calcium chlorine
calcium + chlorine --> calcium chloride
calcium(s) + chlorine(g) --> calcium chlorine(s)
calcium(s) + chlorine(g) --> calcium chloride(g)
calcium(s) + chlorine(g) --> calcium chloride(s)
2. Aluminium (group IIIA) reacts rapidly with fluorine (group VIIA) to form aluminium fluoride. The correct formula of the product is ….
a. AlF(s)
b. AlF2(s)
c. AlF3(s)
d. Al3F(s)
e. Al2F(s)
3. Balance the following equation. What is the sum of the coefficients of the reactants and products?
C3H8O2 + O2 --> CO2 + H2O
a. 17
b. 15
c. 12
d. 10
e. 9
4. Balance the following equation. What is the sum of the coefficients of the reactants?
C6H8O6 + O2 --> CO2 + H2O
a. 16
b. 15
c. 10
d. 5
e. 6
5. Balance the following equation. What is the sum of the coefficients of the reactants?
C12H22O11 + O2 --> CO2 + H2O
a. 7
b. 9
c. 10
d. 13
e. 12
6. Balance the following equation. What is the sum of the coefficients of the products?
C + HNO3 --> NO2 + H2O + CO2
a. 6
b. 4
c. 9
d. 7
e. 5
7. Balance the following equation and choose the quantity which is the sum of the coefficients of the reactants and products.
P2H4 --> PH3 + P4
a. 9
b. 12
c. 14
d. 15
e. 16
8. Balance the following equation and choose the quantity which is the sum of the coefficients of the reactants and products.
CuSO4 + KI --> CuI + I2 + K2SO4
a. 13
b. 9
c. 12
d. 11
e. 10
9. Balance the following equation and choose the quantity which is the sum of the coefficients of the products.
SnS2 + HCl --> H2SnCl6 + H2S
a. 8
b. 7
c. 6
d. 5
e. 3
10. Balance the following equation and choose the quantity which is the sum of the coefficients of the products.
CS2 + Cl2 --> CCl4 + S2Cl2
a. 6
b. 5
c. 4
d. 3
e. 2
11. Balance the following equation and choose the quantity which is the sum of the coefficients of the reactants and products.
I2 + Na2S2O3 --> Na2S4O6 + NaI
a. 8
b. 4
c. 6
d. 5
e. 9
12. Potassium, with atomic number 19, reacts rapidly with fluorine to form potassium fluoride. The correct answer of the balanced equation is ….
a. K(s) + 3F(g) --> KF3(s)
b. K(s) + F2(g) --> KF2(s)
c. 2K(s) + F2(g) --> 2KF(s)
d. K(s) + F(g) --> KF(s)
e. K2(s) + F2(g) --> 2KF(s)
13. The correct answer about the balanced chemical equation of forming aluminium oxide is ….
a. 2Al(s) + O(g) --> Al2O(s)
b. Al(s) + O(g) --> AlO(s)
c. 2Al(s) + O2(g) --> 2AlO(s)
d. 4Al(s) + 3O2(g) --> 2Al2O3(s)
e. 2Al2(s) + 3O2(g) --> 2Al2O3(s)
14. One of the following equations is incorrectly balanced. The equation is ….
a. N2(g) + 3H2(g) --> 2NH3(g)
b. 2Fe(s) + 3O2(g) --> 2Fe2O3(s)
c. Ca(s)+2HCl(aq) --> CaCl2(aq)+H2(g)
d. 3Mg(s) + N2(g) --> Mg3N2(s)
e. 2H2(g) + O2(g) --> 2H2O(l)

THERMOCHEMISTRY QUIZ Part VI

1. A coffee cup calorimeter initially contains 125 g of water, at a temperature of 24.2oC. Ammonium nitrate (NH4NO3, 7.07 g), also at 24.2oC, is added to the water, and the final temperature is 18.3oC. What is the heat of solution of ammonium nitrate in kJ/mol? The specific heat capacity of the solution is 4.18 J/oC g. (Ar N = 14, O = 16, H = 1).
a. 39.5
b. 37.3
c. 34.9
d. 32.2
e. 30.1
2. A 0.0500 L sample of 0.500 M barium nitrate is added to 0.0500 L of 0.500 M magnesium sulfate in a calorimeter whose total heat capacity is 455 J/oK. The temperature increase is 1.43oK. Calculate Ho in kJ for the following reaction.
Ba(NO3)2(aq) + MgSO4(aq) --> BaSO4(s) + Mg(NO3)2(aq)
a. -32.0
b. -30.0
c. -28.0
d. -26.0
e. -24.0
3. The combustion of 0.1584 g of benzoic acid increases the temperature of a bomb calorimeter by 2.54oC. The energy released by combustion of benzoic acid is 26.42 kJ/g. A 0.2130 g sample of vanillin (C8H8O3) is then burned in the same calorimeter. The temperature increases by 3.25oC. What is the energy of combustion (kJ/mole) of vanillin?
a. 3.22 x 103
b. 3.08 x 103
c. 2.74 x 103
d. 3.46 x 103
e. 3.82 x 103
4. When 2.62 g of lactic acid, C3H6O3, is burned in a calorimeter whose heat capacity is 21.7 kJ/oK, the temperature increases by 1.800oK. Calculate the heat of combustion of lactic acid in kJ per mole. (Atomic weights: C = 12, H = 1, O = 16).
a. 3.08 x 103
b. 1.68 x 103
c. 1.54 x 103
d. 1.48 x 103
e. 1.22 x 103
5. A 50.0 g piece of copper at 100oC is put into an insulated vessel containing 250 mL of water at OoC. What will be the final temperature (oC) of the water? The specific heat of water and copper are 4.18 J/goC and 0.385 J/goC respectively.
a. 50.0
b. 7.85
c. 5.62
d. 3.25
e. 1.87
6. The specific heat capacity of graphite is 0.71 J/oC g. How much heat energy (kJ) is required to raise the temperature of 850 g of graphite by 150oC?
a. 99
b. 91
c. 86
d. 75
e. 62
7. When 325 J of heat is added to 23.6 g of octane, C8H18, the temperature increases by 6.20oC. Calculate the molar heat capacity of octane (J/moleoC). (Ar C = 12, H = 1).
a. 288
b. 254
c. 235
d. 195
e. 179
8. A 50.0 g piece of copper at 100oC is put into an insulated vessel containing 250 mL of water at OoC. What will be the final temperature (oC) of the water? The specific heat of water and copper are 4.18 J/goC and 0.385 J/goC respectively.
a. 50.0
b. 7.85
c. 5.62
d. 3.25
e. 1.87
9. The specific heat capacity of graphite is 0.71 J/oC g. How much heat energy (kJ) is required to raise the temperature of 850 g of graphite by 150oC?
a. 99
b. 91
c. 86
d. 75
e . 62
10. When 325 J of heat is added to 23.6 g of octane, C8H18, the temperature increases by 6.20oC. Calculate the molar heat capacity of octane (J/moleoC). (Ar C=12, H = 1).
a. 288
b. 254
c. 235
d. 195
e. 179

THERMOCHEMISTRY QUIZ Part V

1. The combustion of B2H6 occurs according to the following equation. Using the enthalpies of formation, calculate the energy (kJ) released when 4.00 g of B2H6 reacts. (Ar B = 10.8, O = 16, H = 1).
B2H6(g) + 3 O2(g) --> B2O3(s) + 3 H2O(g)
Ho B2H6(g) = -57.4 kJ/mole;
Ho B2O3(s) = -1273 kJ/mole;
Ho H2O(g) = -241.8 kJ/mole
a. 1246
b. 1941
c. 522
d. 426
e. 281
2. Oxygen difluoride reacts with water according to the following equation. Using the enthalpies of formation, calculate the energy (kJ) released when 5.00 g of OF2 reacts.(Ar O = 16, F = 19, H = 1).
OF2(g) + H2O(g) --> O2(g) + 2 HF(g)
Ho H2O(g) = -241.8 kJ/mole
Ho HF(g) = -271.1 kJ/mole
Ho OF2(g) = +17.6 kJ/mole
a. 75.6
b. 62.5
c. 51.8
d. 29.4
e. 12.6
3. Nitroglycerin decomposes via the following process. Given the enthalpies of formation, calculate the energy liberated when 10 g of nitroglycerin is detonated. (Ar C = 12, H = 1, N = 14, O = 16).
4 C3H5(NO3)3(l) --> 6 N2(g) + O2(g) + 12 CO2(g) + 5 H2O(g)
Ho C3H5(NO3)3(l) = -364 kJ/mole
Ho CO2(g) = -393.5 kJ/mole
Ho H2O(g) = -241.8 kJ/mole
a. 196
b. 49
c. -3383
d. -4475
e. -4825
4. The fat, glyceryl trioleate, is metabolized via the following reaction. Given the enthalpies of formation, calculate the energy (kJ) liberated when 1.00 g of this fat reacts. (Ar C = 12, H = 1, O = 16).
C57H107O6(s) + 80 O2(g) --> 57 CO2(g) + 52 H2O(l)
Ho C57H107O6 = -70870 kJ/mole
Ho H2O(l) = -285.8 kJ/mole
Ho CO2(g) = -393.5 kJ/mole
a. 42.6
b. 40.4
c. 37.8
d. 33.4
e. 30.2
5. Using the enthalpies of formation, calculate the energy (kJ) released when 3.00 g of NH3 reacts according to the following equation. (Ar B = 10.8, O = 16, H = 1).
4 NH3(g) + 5 O2(g) --> 4 NO(g) + 6 H2O(g)
Ho NH3(g) = -46.1 kJ/mole
Ho NO(g) = +90.2 kJ/mole
Ho H2O(g) = -241.8 kJ/mole
a. 30.8
b. 34.3
c. 37.2
d. 39.9
e. 42.6
6. Calculate the Ho for the following reaction using the given bond energies.
(H - F = 565 kJ; O - O = 494 kJ; H - O = 463, O - F = 184).
F2O(g) + H2O(g) --> O2(g) + 2 HF(g)
a. -390
b. -360
c. -330
d. -260
e. -230
7. The enthalpy change for the following reaction is 368 kJ. Calculate the average O - F bond energy.
OF2(g) --> O(g) + 2 F(g)
a. 184
b. 242
c. 368
d. 536
e. 736
8. Calculate the Ho for the following reaction using the given bond energies.
(C - H = 414 kJ; F - F = 155 kJ; H - F = 431, C - F = 485).
CH4(g) + 4 F2(g) --> CF4(g) + 4 HF(g)
a. -1678
b. -1598
c. -1542
d. -1422
e. -1388
9. Calculate the Ho for the following reaction using the given bond energies.
(H - Cl = 431 kJ; O - O = 494 kJ; H - O = 463, Cl - Cl = 243).
4 HCl(g) + O2(g) --> 2 H2O(g) + 2 Cl2(g)
a. -169
b. -152
c. -139
d. -120
e. -102

THERMOCHEMISTRY QUIZ Part IV

1. The standard enthalpy of formation of propane, C3H8, is -103.6 kJ/mole. Calculate the heat of combustion of one mole of C3H8. The heats of formation of CO2(g) and H2O(l) are -394 kJ/mole and -285.8 kJ/mole respectively.
a. 2220
b. 2060.0
c. 1856
d. 1721.2
e. -1939.1
2. The standard enthalpy of formation of methanol, CH3OH, is -238.6 kJ mole. Calculate the heat of combustion of one mole of CH3OH. The heats of formation of CO2(g) and H2O(l) are -394 kJ/mole and -285.8 kJ/mole respectively.
a. 1300
b. 1142
c. 976
d. 854
e. 727
3. The heat of formation of CO2(g) is -394 kJ/mole and that of H2O(l) is -286 kJ/mole. The heat of combustion of C5H12 is -3534 kJ/mole. What is the heat of formation of C5H12?
C5H12(l) + 8 O2(g) --> 5 CO2(g) + 6 H2O(l)
a. -7220
b. -152
c. -108
d. +108
e. +152
4. Using the following information calculate the heat of formation of N2H4.
N2H4(l) + O2(g) --> N2(g) + 2 H2O(l)Ho = -622.4 kJ
Hof H2O(l) = -285.9 kJ/mole
a. +98.6
b. +90.4
c. +70.6
d. +50.6
e. +33.5
5. Using the following information calculate the heat of formation of Fe2O3.
Fe2O3(s) + 3 H2(g) --> 2 Fe(s) + 3 H2O(l) Ho = -35.5 kJ
Hof H2O(l) = -285.9 kJ/mole
a. -893.2
b. -822.2
c. -464.4
d. -393.4
e. -250.4
6. Using the following information calculate the heat of formation of CCl4.
CH4(g) + 4 Cl2(g) --> CCl4(g) + 4 HCl(g) Ho = -402 kJ
Hof CH4(g) = -74.85 kJ/mole; Hof HCl(g) = -92.30 kJ/mole
a. -132
b. -108
c. -54.0
d. +54.0
e. +132
7. The heat of formation of PCl3(g) is -287.0 kJ/mole. What is the heat of reaction for the following process?
2 PCl3(g) --> 2 P(s) + 3 Cl2(g)
a. -612.8
b. -306.4
c. +153.2
d. +306.4
e. + 612.8
8. Given the heat of reaction, Ho = -2029.7 kJ, and the indicated heats of formation, determine the heat of formation of NH4NO3(s) in kJ.
2 Al(s) + 3 NH4NO3(s) --> 3 N2(g) + 6 H2O(g) + Al2O3(s)
Hof H2O(g) = -241.8 kJ; Hof Al2O3(s) = -1675.7 kJ
a. +365.6
b. +298.2
c. -298.2
d. -365.6
e. -442.5
9. The heats of formation of CO2(g) and H2O(l) are -394 kJ/mole and -285.8 kJ/mole respectively. Using the data for the following combustion reaction, calculate the heat of formation of C3H8(g).
C3H8(g) + 5 O2(g) --> 3 CO2(g) + 4 H2O(l) Ho = -2221.6 kJ
a. -143.3
b. -103.6
c. 20.4
d. 185.4
e. 212.2
10. The heats of formation of CO2(g) and H2O(l) are -394 kJ/mole and -285.8 kJ/mole respectively. Using the data for the following combustion reaction, calculate the heat of formation of C3H4(g).
C3H4(g) + 4 O2(g) --> 3 CO2(g) + 2 H2O(l) Ho = -1939.1 kJ
a. -143.3
b. -103.8
c. 20.4
d. 185.4
e. 212.2

THERMOCHEMISTRY QUIZ Part III

1. Calculate the value of Ho/kJ for the following reaction using the listed thermochemical equations: 3 NO2(g) + H2O(l) --> 2 HNO3(l) + NO(g)
NH4NO3(s) --> N2O(g) + 2 H2O(l) Ho/kJ = -125.2 kJ
3 NO(g) --> N2O(g) + NO2(g) Ho/kJ = -155.8 kJ
4 NH3(g) + 5 O2(g) --> 4 NO(g) + 6 H2O(l) Ho/kJ = -1169.2 kJ
NO(g) + 12 O2(g) --> NO2(g) Ho/kJ = -56.6 kJ
a. -124.3
b. -95.6
c. -82.6
d. -71.4
e. -56.2
2. Given the following equations and Ho values, determine the heat of reaction (kJ) at 298 K for the reaction: B2H6(g) + 6 Cl2(g) --> 2 BCl3(g) + 6 HCl(g)
BCl3(g) + 3 H2O(l) --> H3BO3(g) + 3 HCl(g) Ho/kJ = -112.5
B2H6(g) + 6 H2O(l) --> 2 H3BO3(s) + 6 H2(g) Ho/kJ = -493.4
1/2 H2(g) + 1/2 Cl2(g) --> HCl(g) Ho/kJ = -92.3
a. +698.2
b. -360.7
c. -545.3
d. -698.2
e. -1376
3. Determine Ho/kJ for the following reaction using the listed enthalpies of reaction: CH4(g) + 1/2 O2(g) --> CO(g) + 2 H2(g)
CH4(g) + 2 O2(g) --> CO2(g) + 2 H2O(l) Ho/kJ = -802 kJ
CH4(g) + CO2(g) --> 2 CO(g) + 2 H2(g) Ho/kJ = +206 kJ
CH4(g) + H2O(g) --> CO(g) + 3 H2(g) Ho/kJ = +247 kJ
a. -25.5
b. -85
c. -92
d. -102
e. -143
4. Calculate the Ho for the following reaction using the listed thermochemical equations: C2H4(g) + H2(g) --> C2H6(g)
C2H4(g) + 3 O2(g) --> 2 CO2(g) + 2 H2O(l) Ho/kJ = -1410.9 kJ
C2H6(g) + 7/2 O2(g) --> 2 CO2(g) + 3 H2O(l) Ho/kJ = -1559.8 kJ
H2(g) + 1/2 O2(g) --> H2O(l) Ho/kJ = -285.8 kJ
a. +178.4
b. +136.9
c. -136.9
d. -178.4
e. -192.4
5. Given the following equations and Ho values, determine the heat of reaction (kJ) at 298 K for the reaction: 3 NO2(g) + H2O(l) --> 2 HNO3(l) + NO(g)
NH3(g) + HNO3(l) --> NH4NO3(s) Ho/kJ = -145.7
NH4NO3(s) --> N2O(g) + 2 H2O(l) Ho/kJ = -125.2
3 NO(g) --> N2O(g) + NO2(g) Ho/kJ = -155.8
4 NH3(g) + 5 O2(g) --> 4 NO(g) + 6 H2O(l) Ho/kJ = -1169.2
NO(g) + 1/2 O2(g) --> NO2(g) Ho/kJ = -56.6
a. -1291.6
b. -805.9
c. -685.9
d. -300.1
c. -70.4
6. Determine Ho/kJ for the following reaction using the listed enthalpies of reaction: N2H4(l) + 2 H2O2(g) --> N2(g) + 4 H2O(l)
N2H4(l) + O2(g) --> N2(g) + 2 H2O(l) Ho/kJ = -622.3 kJ
H2(g) + 1/2 O2(g) --> H2O(l) Ho/kJ = -285.8 kJ
H2(g) + O2(g) --> H2O2(l) Ho/kJ = -187.8 kJ
a. -864.3
b. -818.3
c. -745.6
d. -642.2
e. -604.3
7. Calculate the value of Ho/kJ for the following reaction using the listed thermochemical equations: 2 H2O2(l) 2 H2O(l) + O2(g)
2 H2(g) + O2(g) --> 2 H2O(g) Ho/kJ = -483.6 kJ
H2O(l) --> H2O(g) Ho/kJ = +44.0 kJ
H2(g) + O2(g) --> H2O2(l) Ho/kJ = -187.6 kJ
a. -208.4
b. -196.4
c. -188.4
d. -176.5
e. -164.2
8. Given the following equations and Ho values, determine the heat of reaction (kJ) at 298 K for the reaction:
4 C(s) + 8 H2(g) + 2 O2(g) --> 3 CH4(g) + CO2(g) + 2 H2O(l)
C(s) + 1/2 O2(g) --> CO(g) Ho/kJ = -110.54
CO(g) + 1/2 O2(g) --> CO2(g) Ho/kJ = -282.97
H2(g) + 1/2 O2(g) --> H2O(l) Ho/kJ = -285.85
C(s) + 2 H2(g) --> CH4(g) Ho/kJ = -74.85
a. +1189.76
b. +181.7
c. -181.7
d. -331.6
e. -1189.76
9. Given the following equations and Ho values, determine the heat of reaction (kJ) at 298 K for the reaction: 4 H2O(g) + 3 Fe(s) --> Fe3O4(s) + 4 H2(g)
H2(g) + 1/2 O2(g) --> H2O(g) Ho/kJ = -285.83
FeO(s) + 1/2 O2(g) --> Fe3O4(s) Ho/kJ = -302.4
FeO(s) + H2(g) --> Fe(s) + H2O(g) Ho/kJ = -13.8
a. -602.0
b. -391.7
c. +391.7
d. -24.8
e. +24.8
10. Which of the following equations represents a reaction that provides the heat of formation of hydroxylamine (NH2OH)?
a. NH3(g) + O(g) --> NH2OH(l)
b. ½ N2(g) + 1½ H2(g) + ½ O2(g) --> NH2OH(l)
c. N(g) + 3 H(g) + O(g) --> NH2OH(l)
d. N2(g) + 3 H2O2(l) --> 2 NH2OH(l) + 2 O2(g)
e. NH3(g) + 1/2 O2(g) --> NH2OH(l)
11. Which of the following equations represents a reaction that provides the heat of formation of ethanol (CH3CH2OH)?
a. 2 C(s) + 6 H(g) + O(g) --> CH3CH2OH(l)
b. 2 C(s) + 3 H2(g) + 1/2 O2(g) --> CH3CH2OH(l)
c. CH2 = CH2(g) + H2O(l) --> CH3CH2OH(l)
d. 2 CO(g) + 3 H2(g) --> CH3CH2OH(l) + 1/2 O2(g)
e. 2 CO2(g) + 6 H2(g) --> CH3CH2OH(l) + 3 H2O(l)
12. Which of the following equations represents a reaction that provides the heat of formation of hydrogen peroxide (H2O2)?
a. 2 H2O(l) --> H2O2(l) + H2(g)
b. H2(g) + O2(g) --> H2O2(l)
c. 2 H(g) + 2 O(g) --> H2O2(l)
d. H2O(l) + 12 O2(g) --> H2O2(l)
e. 2 H(g) + O2(g) --> H2O2(l)
13. Which of the following equations represents a reaction that provides the heat of formation of carbon dioxide (CO2)?
a. 2 CO(g) --> CO2(g) + C(s)
b. CO(g) + 1/2 O2(g) --> CO2(g)
c. C(s) + O2(g) --> CO2(g)
d. CO(g) + O(g) --> CO2(g)
e. C(s) + 2 O(g) --> CO2(g)
14. Which of the following equations represents a reaction that provides the heat of formation of hydrogen peroxide (H2O2)?
a. 2 H2O(l) --> H2O2(l) + H2(g)
b. H2(g) + O2(g) --> H2O2(l)
c. 2 H(g) + 2 O(g) --> H2O2(l)
d. H2O(l) + 12 O2(g) --> H2O2(l)
e. 2 H(g) + O2(g) --> H2O2(l)
15. Which of the following equations represents a reaction that provides the heat of formation of ethane (CH3CH3)?
a. CH2=CH2(g) + 2 H2(g) --> CH3CH3(g)
b. 2 CH4(g) --> CH3CH3(g) + H2(g)
c. 2 C(s) + 3 H2(g) --> CH3CH3(g)
d. 2 C(s) + 6 H(g) --> CH3CH3(g)
e. CH-CH(g) + 2 H2O(g) --> CH3CH3(g) + O2(g)

THERMOCHEMISTRY QUIZ Part II

1. Given the following equations and Ho values, determine the heat of reaction (kJ) at 298 K for the reaction: N2(g) + O2(g) --> 2 NO(g)
4 NH3(g) + 5 O2(g) --> 6 H2O(l) + 4 NO(g) Ho/kJ = -6134
NH3(g) + 3O2(g) --> 2 N2(g) + 6 H2O(l) Ho/kJ = -790
a. +177
b. +89
c. -89
d. -177
e. -1403
2. Calculate the value of Ho/kJ for the following reaction using the listed thermochemical equations: CuCl2(s) + Cu(s) --> 2 CuCl(s)
Cu(s) + Cl2(g) --> CuCl2(s) Ho/kJ = -206 kJ
2 Cu(s) + Cl2(g) --> 2 CuCl(s) Ho/kJ = -36 kJ
a. -242
b. -170
c. +121
d. +170
e. +242
3. Given the following equations and Ho values, determine the heat of reaction (kJ) at 298 K for the reaction: XeF2(s) + F2(g) --> XeF4(s)
Xe(g) + F2(g) --> XeF2(s) Ho/kJ = -164
Xe(g) + 2 F2(g) --> XeF4(s) Ho/kJ = -262
a. -426
b. -213
c. -98
d. +98
e. +426
4. Calculate the value of Ho/kJ for the following reaction using the listed thermochemical equations: N2(g) + ½ O2(g) --> N2O(g)
2 NH3(g) + 3 N2O(g) --> 4 N2(g) + 3 H2O(l) Ho/kJ = -1010 kJ
4 NH3(g) + 3 O2(g) --> 2 N2(g) + 6 H2O(l) Ho/kJ = -1531 kJ
a. -489
b. -163
c. -81.5
d. +81.5
e. +163
5. Calculate Ho/kJ for the following reaction using the listed standard enthapy of reaction data: (C2H5)2O(l) --> C4H9OH(l)
C4H9OH(l)+6O2(g) --> 4 CO2(g) + 5 H2O(g) Ho/kJ=-2456.1 kJ
(C2H5)2O(l) + 6 O2(g) --> 4 CO2(g) + 5 H2O(g) Ho/kJ = -2510.0 kJ
a. -4966.1
b. -2483.1
c. -53.9
d. +53.9
e. +4966.1
6. Given the following equations and Ho values, determine the heat of reaction at 298 K for the reaction: P4(s) + 10 Cl2(g) --> 4 PCl5(g)
P4(s) + 6 Cl2(g) --> 4 PCl3(l) Ho/kJ = -1150
PCl3(l) + Cl2(g) --> PCl5(g) Ho/kJ = -111
a. +1261
b. +399
c. -399
d. -1261
e. -1594
7. Given the following equations and Ho values, determine the heat of reaction at 298 K for the reaction which occurs in a welder's acetylene torch:
2 C2H2(g) + 5 O2(g) --> 4 CO2(g) + 2 H2O(l)
H2(g) + 1/2 O2(g) --> H2O(l) Ho/kJ = -285.8
2 C(s) + H2(g) --> C2H2(g) Ho/kJ = +226.7
C(s) + O2(g) --> CO2(g) Ho/kJ = -393.5
a. -285.8
b. -571.6
c. -1574.0
d. -2145.6
e. -2599.0
8.Given the following equations and Ho values, determine the heat of reaction at 298 K for the reaction: C(s) + 2 H2(g) --> CH4(g)
C(s) + O2(g) --> CO2(g) Ho/kJ = -393.5
H2(g) + 1/2 O2(g) --> H2O(l) Ho/kJ = -285.8
CO2(g) + 2 H2O(l) --> CH4(g) + 2 O2(g) Ho/kJ = +890.3
a. +211.0
b. +74.8
c. -74.8
d. -192.2
e. -211.0
9. Calculate Ho/kJ for the following reaction using the listed standard enthapy of reaction data: 2 N2(g) + 5 O2(g) --> 2 N2O5(s)
N2(g) + 3 O2(g) + H2(g) --> 2 HNO3(aq) Ho/kJ = -414.0
N2O5(s) + H2O(l) --> 2 HNO3(aq) Ho/kJ = -86.0
2 H2(g) + O2(g) --> 2 H2O(l) Ho/kJ = -571.6
a. -42.2
b. -71.2
c. -84.4
d. -121.8
e. -243.6

THERMOCHEMISTRY QUIZ Part I

1. The statement which best describes a chemical reaction in which energy released is ….
a. exothermic and has a negative ΔH.
b. exothermic and has a positive ΔH.
c. endothermic and has a negative ΔH.
d. endothermic and has a positive ΔH.
2. When a chemical reaction occurs in which the products are more stable than the reactants ....
a. the potential energy of the reactants is completely transferred to the products.
b. the potential energy of the products is greater than the potential energy of the eactants.
c. the total amount of kinetic and potential energy of the chemicals in the reaction increases.
d. some of the potential energy of the reactants is transformed into kinetic energy.
e. the total amount of kinetic and potential energy of the chemicals in the reaction decreases.
3. The statement which gives the correct relationship between the sign of the change in internal energy and the system is ….
a. the change in internal energy is negative if Efinal is greater than Einitial.
b. The change in internal energy is positive if energy flows out of the surroundings and into the system.
c. The change in internal energy is positive if Einitial is greater than Efinal.
d. The change in internal energy is negative if energy flows out of the surroundings and into the system.
e. The change in internal energy is positive if energy flows out of the system and into the surroundings.
4. Which phase change is exothermic?
a. H2O(s) --> H2O(l)
b. H2O(l) --> H2O(s)
c. H2O(s) --> H2O(g)
d. H2O(l) --> H2O(g)
5. Which phase change is endothermic?
a. gas --> solid
b. gas --> liquid
c. liquid --> solid
d. liquid --> gas
6. The heat required to change 1 gram of a liquid at its normal boiling point to a gas at the same temperature is called the heat of ....
a. vaporization
b. fusion
c. reaction
d. formation
7. Solid A at 80 C is immersed in liquid B at 60 C. Which statement correctly describes the energy changes between A and B?
a. A releases heat and B absorbs heat.
b. A absorbs heat and B releases heat.
c. Both A and B absorb heat.
d. Both A and B release heat.
8. When ammonium chloride crystals are dissolved in water, the temperature of the water decreases. What does this temperature change indicate about the dissolving of ammonium chloride in water?
a. It is an endothermic reaction because it absorbs heat.
b. It is an endothermic reaction because it releases heat.
c. It is an exothermic reaction because it absorbs heat.
d. It is an exothermic reaction because it releases heat.
9. For a chemical reaction carried out at … the change in internal energy can be attributed to ….
a. constant volume; heat transfer
b. constant pressure; work
c. constant volume; work
d. constant pressure; heat transfer
e. constant volume; work and heat transfer
10. In order to ensure that comparisons of changes in enthalpy for reactions can be made, measurements of changes in enthalpy must be made under the conditions of ….
a. 298 K, 1 atm pressure, 1 M concentration for ions, and specified physical states.
b. 273 K, 1 atm pressure, 1M concentration, and specified physical states.
c. 298 K, 1 atm pressure, and 1 M concentration.
d. 273 K, 1 atm pressure, and 1M concentration.
e. 0°C, 1 atm pressure, 1M concentration, and specified physical states.

BOND ENERGY

Bond energies (BE) are defined as the energies required to break the chemical bonds of substances. So this is an endotermic process, the value is positive. In calculating the enthalpy change of a reaction, you can use the following formula :
DHreaction = SUM (BEreactants) - SUM (BEproducts)
Now do the following exercise :
The bond energy (kJ/mol) for H2, F2, and HF are 436, 158 and 568 kJ/mol respectively. Calculate the enthalpy change of : H2(g) + F2(g) --> 2 HF
Since bond energies are given, use the monoatomic gases.
After calculating the enthalpy change, draw a diagram.

STANDARD ENTHALPIES FORMATION

Using Formulas to Calculate enthalpy change.
The enthalpy change of a reaction can be calculated through the use of formulas. This formula depends on whether enthalpies of formation or bond energies are available.
When standard enthalpies of formation, DHfo, for all products and reactants are available, you have to use the following formula :
DHreaction = SUM (DHproducts) - SUM (DHreactants)
For simplicity in formulation, use DH to represent DHfo in the above formulas. D is delta, DH is enthalpy change, f is formation, and o is standard.
Calculate the enthalpy change of the following reactions by using a table of DHfo.
1. Calculate the enthalpy change of burning methane gas.
2. Calculate the combustion enthalpy of propane gas and butane gas.

HESS' LAW TASK

Hallo students, now you have to develop your understanding about Hess' law. Hess' law states about the summation of reaction, to sum the enthalpy change of step reactions in finding the enthalpy change of target reaction.

This diagram is an energy level diagram or named as an enthalpy diagram.

Look at the diagram, then write the step reactions and the target reaction. Okay, please do right now.