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

STOICHIOMETRY QUIZ Part II

1.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
2.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
3.One dm3 of CxHy gas burns in 2 dm3 of an oxygen gas. If there is 1 dm3 of CO2(g), the chemical formula of CxHy is ….
a.CH4
b.C2H2
c.C2H4
d.C3H3
e.C3H6
4.Ethane gas, C2H6 is burned in air. The volume of ethane gas is 4,0 dm3. The volume of oxygen gas at the same P and T which needed in the burning is ….
a.3,5 dm3
b.7,0 dm3
c.10,5 dm3
d.14,0 dm3
e.28,0 dm3
5. Eight litters of hydrogen gas combines with x litters of chlorine gas to form eight litters of hydrogen chloride gas. The value of x is ….
a.2
b.4
c.6
d.8
e.10
6.Silver (Atomic mass 107.87) has two naturally-occurring isotopes with isotopic mass of 106.91 and 108.90. What is the percentage abundance of the heavier isotope?
a.47.24
b.51.82
c.48.16
d.49.05
e.50.95
7.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
8.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)
9.Which of the following organic compounds has the lowest molecular mass? (ArC = 12, N = 14, H = 1).
a.C7H14
b.C6H10N2
c.C4H8N4
d.C7H11N
e.C5H11N3

STOICHIOMETRY QUIZ Part I

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)  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=30g and the mass of NO2=46g. 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

THE ANSWER OF STOICHIOMETRY PROBLEMS Part 2

2. Hydrochloric acid is added to 1,3 grams of zink (Ar 65). If molarity of acid is 3 mol/L, answer the following questions.

a. 2HCl(aq) + Zn(s) --> ZnCl₂(aq) + H2(g)

2H+(aq)+2Cl-(aq)+Zn(s) --> Zn2+(aq) + 2Cl-(aq) + H2(g)

2H+(aq) + Zn(s) --> Zn2+(aq) + H2(g)

b.Determine the minimum volume of acid needed in this reaction.

n(Zn) = 1,3g/65g.mol-1 = 0,02 mol

n(HCl) = 2/1 . 0,02 = 0,04 mol

V(HCl) = 0,04 mol/3 mol/L = 0,013L= 13 mL

c. Calculate the gas produced at:

1) STP

n(H2) = 0,02 mol.
V(H2) = 0,02 mol x 22,4 L/mol= 0,448 L (448mL).

2) 1 atm and 27 degree's celcius

PV = nRT

1.V(H2) = 0,02. 0,082. 300

V(H2) = 0,492 L ( 492 mL)

3) the same T and P with nitrogen gas (Ar N = 14) that its mass of 1 L is 2 grams.

V(H2) = n(H2)/n(N2) x V(N2); n(N2) = 2/28 = 1/14 mol

V(H2) = 0,04/1/14 x 1L = 0,04 x 14 L = 0,56 L.

d. If zink used is 80% from its ore, calculate the mass of ore used.

Mass of ore = 100/80 x 1,3 g = 1,625 grams.

3. An aliage contains 90% of aluminium (Ar 27) and 10% of cuprum (Ar 63,5) is used to produce hydrogen gas. Hydrochloric acid is added to this aliage and produces 6,72 L gas at STP.

a. Write down the molecular equation and ionic equation.

2Al(s) + 6HCl(aq) --> 2AlCl3(aq) + 3H2(g)

2Al(s) + 6H+(aq)+6Cl-(aq) --> 2Al3+(aq)+6Cl-(aq)+3H2(g)

2Al(s) + 6H+(aq) --> 2Al3+(aq) + 3H2(g)

b. Calculate the mass of aliage.

n(H2) = 6,72L/22,4L.mol-1 = 0,3 mol

n(Al) = 2/3 x 0,3 mol = 0,2 mol.

m(Al) = 0,2 mol x 27 g/mol = 5,4 g

m(ore) = 100/90 x 5,4 g = 6 g.

c. If the minimum volume of acid used is 200 mL, predict the
molarity of this acid.

n(HCl) = 6/3 x 0,3 mol = 0,6 mol.

M(HCl) = 0,6 mol/0,2 L = 3 mol/L.

4. A mol of metal, M reacts with sulfuric acid 2M, produced 33,6 L hydrogen gas at STP. Answer the questions below.

a. Determine the formula of salt produced.

2M(s) + 3H2SO4(aq) --> M2(SO4)x(aq) + 3H2(g)
x = 3, Formula of salt = M2(SO4)3

n(H2) = 33,6 L / 22,4 L.mol-1 = 1,5 mol

b. Determine the oxidation number of M.

Oxidation number of M in salt is +3.

c. Write down the molecular equation and ionic equation.

2M(s) + 3H2SO4(aq) --> M2(SO4)3(aq) + 3H2(g)

2M(s)+6H+(aq)+3SO42-(aq)-->2M3+(aq)+3SO42-(aq)+3H2(g)

2M(s) + 6H+(aq) --> 2M3+(aq) + 3H2(g)

d. Calculate the minimum volume of acid needed.

n(H2SO4) = 3/3 x 1,5 mol = 1,5 mol

V(H2SO4) = 1,5 mol/ 2mol.L-1 = 0,75 L (750 mL)

5. FeS(Mr=88) is reacted with hydrochloric acid according to the following reaction:

FeS(s)+2HCl(aq) → FeCl2(aq)+H2S(g)

If this reaction produces 8 L of H2S gas, and at the same T and
P, 1 mol of H2S(g) = 20 L, answer the questions below.

a. Write down the ionic equation.

FeS(s)+2H+(aq)+2Cl-(aq) → Fe2+(aq)+2Cl-(aq)+H2S(g)

FeS(s) + 2H+(aq) → Fe2+(aq) + H2S(g)

b. Calculate the mass of FeS.

n(H2S) = 8L/20L.mol-1 = 0,4 mol

n(FeS) = 0,4 mol

m(FeS) = 0,4 mol x 88 g = 35,2 g

c. If an ore contains 70,4% FeS, calculate the mass of ore.

m(ore) = 100/70,4 x 35,2 g = 50%

d. The acid used is 4M. Determine the minimum volume of acid needed.

n(HCl) = 2/1 x 0,4 mol= 0,8 mol.

V(HCl) = 0,8 mol / 4 mol.L-1 = 0,2 L (200 mL)

THE ANSWER OF STOICHIOMETRY PROBLEMS Part 1

1.Write down the molecular equation and ionic equation, then state the name of the products.

a.Ba(OH)2(aq)+2HCl(aq)--> BaCl2(aq) + 2H2O(l)
Barium chloride
Ba2+(aq)+2OH-(aq)+2H+(aq)+2Cl-(aq)-->Ba2+(aq)+2Cl-(aq)+2H2O(l)
OH-(aq) + H+(aq) --> H2O(l)

b.CH3COOH(aq)+NaOH(aq)--> CH3COONa(aq)+H2O(l)
Sodium acetate
CH3COOH(aq)+Na+(aq)+OH(aq)-->CH3COO-(aq)+Na+(aq)+H2O(l)
CH3COOH(aq)+OH(aq)-->CH3COO-(aq)+H2O(l)

c.H2SO4(aq)+2NH3(aq)-->(NH4)2SO4(aq)
Ammonium sulfate
2H+(aq)+SO42-(aq)+2NH3(aq)-->2NH4+(aq)+SO42-(aq)
2H+(aq)+2NH3(aq)-->2NH4+(aq)

d.CaO(s) + 2HCl(aq) --> CaCl2(aq) + H2O(l)
Calcium chloride
CaO(s)+2H+(aq)+2Cl-(aq)-->Ca2+(aq)+2Cl-(aq)+H2O(l)
CaO(s)+2H+(aq)-->Ca2+(aq)+H2O(l)

e.CO2(g)+Ca(OH)2(aq)--> CaCO3(s)+H2O(l)
Calcium carbonate
CO2(g)+Ca2+(aq)+2OH-(aq)-->CaCO3(s)+H2O(l)

f.2HCl(aq)+Ca(s)--> CaCl2(aq)+H2(g)
Calcium chloride
2H+(aq)+2Cl-(aq)+Ca(s)-->Ca2+(aq)+2Cl-(aq)+H2(g)
2H+(aq)+Ca(s)-->Ca2+(aq)+H2(g)

g.H2SO4(aq)+Mg(s)--> MgSO4(aq)+H2(g)
Magnesium sulfate
2H+(aq)+SO42-(aq)+Mg(s)-->Mg2+(aq)+SO42-(aq)+H2(g)
2H+(aq)+Mg(s)-->Mg2+(aq)+H2(g)

h.6H2SO4(aq)+2Fe(s)-->Fe2(SO4)3(aq)+3SO2(g)+6H2O(l)
Iron(III) sulfate, sulfur dioxide
12H+(aq) + 6SO42-(aq) + 2Fe(s) --> 2Fe3+(aq) + 3SO42-(aq) + 3SO2(g)+ 6H2O(l)
12H+(aq) + 3SO42-(aq) + 2Fe(s) --> 2Fe3+(aq) + 3SO2(g)+ 6H2O(l)

i.8HNO3(aq)+3Zn(s)-->3Zn(NO3)2(aq)+2NO(g)+4H2O(l)
Zink nitrate, nitrogen monooxide
8H+(aq)+8NO3-(aq)+3Zn(s)-->3Zn2+(aq)+6NO3-(aq)+2NO(g)+4H2O(l)
8H+(aq)+2NO3-(aq)+3Zn(s)-->3Zn2+(aq)+2NO(g)+4H2O(l)

j.2HNO3(aq) + Ag(s) --> AgNO3(aq) + NO2(g) + H2O(l)
Silver nitrate, nitrogen dioxide
2H+(aq)+2NO3-(aq)+Ag(s)-->Ag+(aq)+NO3-(aq)+NO2(g)+H2O(l)
2H+(aq)+NO3-(aq)+Ag(s)-->Ag+(aq)+NO2(g)+H2O(l)

k.AgNO3(aq) + NaCl(aq) --> AgCl(s) + NaNO3(aq)
Silver chloride, Sodium nitrate
Ag+(aq)+NO3-(aq)+Na+(aq)+Cl-(aq)-->AgCl(s)+Na+(aq)+NO3-(aq)
Ag+(aq)+Cl-(aq)-->AgCl(s)

l.NH4Cl(aq)+NaOH(aq) --> NaCl(aq) + NH3(g) + H2O(l)
Sodium chloride,ammonia
NH4+(aq)+Cl-(aq)+Na+(aq)+OH-(aq)-->Na+(aq)+Cl-(aq)+NH3(g)+H2O(l)
NH4+(aq)+OH-(aq)-->NH3(g)+H2O(l)

STOICHIOMETRY PROBLEMS

1.Write down the molecular equation and ionic equation, then state the name of the products.
a.A solution of barium hydroxide reacts with hydrochloric acid
b.Acetic acid reacts with a solution of sodium hydroxide.
c.Sulfuric acid reacts with a solution of ammonia.
d.Calcium oxide reacts with hydrochloric acid.
e.Carbon dioxide is added to calcium hydroxide solution.
f.Hydrochloric acid is added to calcium.
g.Dilluted sulfuric acid is added to magnesium.
h.Concentrated of sulfuric acid is added to iron.
i.Dilluted nitric acid is added to zink.
j.Concentrated nitric acid is added to silver.
k.A solution of silver nitrate reacts with a solution of table salt produces a precipitate.
l.A solution of ammonium chloride is added to a solution of sodium hydroxide, a gas will be produced.

2.Hydrochloric acid is added to 1,3 grams of zink (Ar 65). If molarity of acid is 3 mol/L, answer the following questions.
a.Write down the molecular equation and the ionic equation.
b.Determine the minimum volume of acid needed in this reaction.
c. Calculate the gas produced at:
1)STP
2)1 atm and 27 degree's celcius
3)the same T and P with nitrogen gas that its mass of 1 L is 2 grams.
d.If zink used is 80% from its ore, calculate the mass of ore used.

3.An aliage contains 90% of aluminium (Ar 27) and 10% of cuprum (Ar 63,5) is used to produce hydrogen gas. Hydrochloric acid is added to this aliage and produces 6,72 L gas at STP.
a.Write down the molecular equation and ionic equation.
b.Calculate the mass of aliage.
c.If the minimum volume of acid used is 200 mL, predict the molarity of this acid.

4.A mol of metal, M reacts with sulfuric acid 2M, produced 33,6 L hydrogen gas at STP. Answer the questions below.
a.Determine the formula of salt produced.
b.Determine the oxidation number of M.
c.Write down the molecular equation and ionic equation.
d.Calculate the minimum volume of acid needed.

5.FeS(Mr=88)is reacted with hydrochloric acid according to the following reaction:
FeS(s)+2HCL(aq) → FeCl2(aq)+H2S(g)
If this reaction produced 8 L of H2S gas, and at the same T and P, 1 mol of H2S gas = 20 L, answer the questions below.
a.Write down the ionic equation.
b.Calculate the mass of FeS.
c.If an ore contains 70,4% FeS, calculate the mass of ore.
d.The acid used is 4M. Determine the minimum volume of acid needed.

SOAL STOIKIOMETRI

1.Cuplikan bubuk besi sebanyak 5 gram dipanaskan dengan gas klor menghasilkan 10 gram besi(II) klorida, FeCl2’ (Ar Fe = 56, Cl = 35,5) kadar besi dalam cuplikan tersebut adalah …
A.4,41 %
B.14,20%
C.71,00%
D.88,20%
E.100,00%
2.Sebanyak 76 gram campuran gas metana dan etana dibakar sempurna sehingga dihasil kan 220 gram gas CO2. Jika Ar C = 12, H = 1, dan O = 16, maka massa gas metana di dalam campuran gas tersebut adalah ….
A.160 gram
B.60 gram
C.16 gram
D.12 gram
E. 6 gram
3.Satu mol logam L bereaksi dengan asam sulfat menghasilkan 33,6 liter gas hidrogen (STP), Rumus garam yang terbentuk adalah ….
A.LSO4
B.L2(SO4)5
C.L(SO4)2
D.L(SO4)5
E.L2(SO¬4)3
4.Sebanyak x gram FeS (Mr = 88) direaksikan dengan asam klorida menurut reaksi:
FeS + 2 HCL → FeCl2 + H2S
Pada akhir reaksi diperoleh 8 liter gas H2S. Jika pada keadaan tersebut satu mol gas H2S bervolum 20 liter, maka nilai x adalah ….
A.8,8
B.17,6
C.26,4
D.35,2
E.44,0
5.Pada pembakaran sempurna suatu hidrokarbon diperlukan 20 g oksigen. Jika pada proses ini terbentuk 9 gram air, maka rumus hidrokarbon tersebut adalah .…(Ar H = 1, O = 16 )
A.C2H2
B.C2H4
C.C2H6
D.C3H8
E.C4H10
6.Suatu cuplikan senyawa PbCO3.xPb(OH)2 yang direaksikan dengan asam sulfat berlebih menghasilkan PbSO4(s), H2O(l), dan CO2(g). jika gas CO2 yang dihasilkam 0,5 mol permol PbSO4, maka nilai x adalah ….
A.1
B.2
C.3
D.5
E.25
7.Asetilena yang digunakan sebagau bahan bakar dalam nyala las dapat dihasilkan dari reaksi antara kalsium karbida dan air. Berapa garam asetilena akan dibentuk dari 0,5 mol kalsium karbida? (Diketahui A¬r H = 1, C = 12, O = 16, dan Ca= 40).
A.13
B.15
C.20
D.26
E.39
8.Pupuk urea dapat dibuat dengan mereaksikan NH3 dan CO2 menurut reaksi:
2NH3 + CO2 → CO(NH2)2 + H2O Jika Ar¬ N= 14, C = 12 O = 16, maka untuk membuat 150 kg pupuk urea diperlukan NH3 sebanyak ....
A.33 kg
b. 43 kg
C. 51 kg
D. 68 kg
E. 85 kg
9.Berdasarkan reaksi elektrolisis: 2Al2O3 --> 4Al + 3O2, maka massa aluminium yang dihasilkan dari 100 ton bauksit murni (Al = 27, O = 16) adalah ….
A.19,0 ton
B.47,0 ton
C.52,9 ton
D.66,6 ton
E.80,0 ton
10.Sebanyak 40 mL gas hidrokarbon CnH2n memerlukan 600 mL udara (mengandung 20% oksigen) untuk pembakaran sempurna. Semua gas diukur pada suhu dan tekanan yang sama. Rumus hidrokarbon tersebut adalah ….
a.CH2
b.C2H4¬
c.C3H6
d.C4H8
e.C5H10
11.Secara teoritis, banyaknya cuplikan dengan kadar belerang 80%, yang dapat menghasilkan 8 gram SO3 adalah …. (O = 16, S = 32)
a.3 g
b.4 g
c.5 g
d.6 g
e.8 g
12.Jika diketahui hemoglobin (Mr = 68.000) mengandung 0,33% massa besi, maka jumlah atom Fe (Ar = 56) dalam molekul hemoglobin adalah ….
a.3
b.4
c.5
d.6
e.7
13.Sebanyak 2 gram metana (Mr = 16) dibakar sempurna dengan O2 murni. Gas CO2 yang terbentuk dialirkan kedalam larutan air kapur, Ca(OH)2, sehingga terbentuk endapan CaCO3 (Mr = 100). Massa endapan yang terbentuk adalah ….
a.7,5 gram
b.10 gram
c.12,5 gram
d.15 gram
e.20 gram
14.Jika unsur A dan B dengan massa sama dicampur dan terjadi reaksi kimia membentuk AB2 (Ar = A = 40, B = 80), unsur A yang tidak bereaksi adalah ….
a.25%
b.40%
c.50%
d.60%
e.75%
15.Suatu paduan logam terdiri dari 90% Al (Ar = 27) dan 10% Cu (Ar = 63,5) digunakan untuk menghasilkan gas H2 dengan cara mereaksikan dengan asam klorida. Jika dihasilkan 6,72 liter gas H2 pada temperatur dan tekanan standar, maka diperlukan paduan sebanyak ….
a.5,4 gram
b.6,0 gram
c.6,6 gram
d.7,6 gram
e.8,0 gram
16.Pada suhu dan tekanan yang sama, massa 2 liter gas X = ½ massa 1 liter gas SO2 (Mr = 64). Mr gas X adalah ….
a.80
b.64
c.34
d.32
e.16
17.Sebanyak 4 liter gas pentana dibakar sempurna menurut reaksi :
C5H12(g)+O2(g)--> H2O(g)+CO2(g) (belum setara). Jika reaksi berlangsung pada keadaan 1 liter gas N2 massanya 1,4 gram (Ar N = 14; L = 6,02.1023), jumlah molekul gas CO2 yang dihasilkan adalah ….
a.3,01.1023
b.6,02.1023
c.7,50.1023
d.9,03.1023
e.12,04.1023