ENTHALPY CHANGE

This diagram shows enthalpy changes.

Why the first arrow tell us that the enthalpy change of reaction is A --> B; and why the second arrow, the enthalpy change is proposed for the reverse reaction, B --> A.

Make a description to explain this evidence by using examples.

DETERMINING ENTHALPY CHANGE

Explain this picture clearly. Look at the calorimeter, there is a metal in the water.
Suggest the metal used in this reaction, find an experimental data and then determine the enthalpy change in kJ/mol.

CALORIMETRY TASK

This is a simple picture of calorimeter. This equipment used in the chemistry laboratory for estimating an enthalpy change in a reaction.
Your task is explaining the use of this equipment, plan an experiment by using this equipment. Choose a certain reaction, for example neutralisation reaction between strong acid, HCl(aq) and strong base, NaOH(aq).
Your explanation including how to use termometer; why there is a difference between the experimental data from scientist and your result.

DIPOLE INDUCED DIPOLE FORCES

Remember about the force between non-polar molecules, for example argon. The element of argon consists of atom, we call as a monoatomic molecule. In argon atom, there is also an intermolecular force, but this force is really very weak because this atom has no dipole moment. The temporary dipoles are only occurred very rare compare with diatomic molecules, as happened in iodine, I2 molecules.

Now, what would happen if we mixed HCl with argon? The electrons on an argon atom are distributed homogeneously around the nucleus of the atom. When an argon atom comes close to a polar HCl molecule, the electrons can shift to one side of the nucleus to produce a very small dipole moment that occurredin a fraction of time. This is very weak temporary dipoles.
According to this evidence, by distorting the distribution of electrons around the argon atom, the polar HCl molecule induces a small dipole moment on this atom, which creates a weak dipole-induced dipole force of attraction between the HCl molecule and the Ar atom.

DIPOLE FORCES

Now lets discuss about dipole forces. The example of this force is HCl as a polar molecule. Polar molecules are sometimes described as "permanent dipoles" or "dipoles". Each molecule has two "poles" permanently. One end (pole) of the molecule has a partial positive charge while the other end has a partial negative charge. The molecules will orientate themselves so that the opposite charges attract effectively.
In the example on the left, hydrogen chloride is a polar molecule with the partial positive charge on the hydrogen and the partial negative charge on the chlorine. A network of partial + and - charges attract molecules one of another.

IONIC FORCES

The physical properties of melting point and boiling point, for example, are related to the strength of attractive forces between molecules. These attractive forces are called Intermolecular Forces.
In an ionic bonding, there is an ionic force. This force is commonly called electrostatic force (Coulomb).
Each Na+ ion and Cl- ion attracts one of another, so that they forms a Crystal.
Although there is a repulsion between inner electrons of Na+ and outer electrons of Cl-, the ionic force is much stronger than the repulsion.
The ionic force is much stronger than the molecular force, so boiling point and melting point of ionic compounds are higher than covalent compounds. The last force will be discussed later.

INDUCED DIPOLE FORCES

Now lets think about intermolecular forces. There are three different forces, force between non-polar molecules, non-polar and polar molecules, and polar molecules.
Forces between non-polar molecules are the weakest of all intermolecular forces.
In the non-polar molecules there are 'Temporary dipoles" which are formed by the shifting of electron clouds within molecules. These temporary dipoles attract or repel the electron clouds of non-polar molecules.
The temporary dipoles exist for a fraction of a second, so a force of attraction exist for that fraction of time. The strength of induced dipole forces depends on how easily electron clouds can be distorted. Atoms or molecules which have many electrons are more easily distorted, because these electrons are far from their nucleus.
Okay, please explain about intermolecular forces in iodine molecules as shown in the picture. Give the reason why in the iodine molecule, atom that has the negative temporary pole is bigger than atom with positive temporary pole,

HYBRIDIZATION PROBLEMS

Look at this diagram. Now think about hybridized sp2 orbitals. The above electron configuration is in the excited state, because one of electrons in the 2s orbital has promoted to the 2py orbital.
1. Write the electron configuration of this atom in the ground state.
2. Which atom has this electron configuration?
3. Why this hybridized orbital called sp2?
4. Give an example of the molecule which has hybridized sp2 orbitals.
5. Apply your understanding of hybridization to another example, for orbitals sp.
6. Explain hybridized sp3 orbitals for ammonia and water.
7. Compare the molecular geometry of methane, ammonia, and water.
8. Explain the reason why methane, ammonia, and water have different molecular shapes, although have the same hybridized orbitals.

HYBRIDIZATION

Lets discuss about hybridization. The simple example is methane, CH4 molecule. Carbon, C-6 (2,4) has four valence electrons. To achieve an octet, C atom needs four electrons and each hydrogen atom needs an electron to achieve a duplet. Each electron from C atom and H atom share one of another, to form polar covalent bond. There are four single covalent bond in CH4 molecule. Although the bonding is polar, the molecule is non polar, because according to the theory of Valence Shell Electron Pair Repulsion (VSEPR), the repulsion between C - H bond is the same.

Okay, when we look at the experimental data, it showed that carbon formed four identical C - H covalent bonds in methane. Its molecular geometry is tetrahedral. From this evident, the carbon atom acts as though it has four unpaired electrons. Linus Pauling invented a hybridization concept. This concept is about the rearrangement of electrons within the valence orbitals of C atom.

To come to the hybridization concept, look at the orbital diagram of carbon atom in the ground state condition.

C-6 : (1s2 2s2 2p2). According to the Hund Rule, the position of two electrons in the p orbitals, are separated into px and py orbitals with the same spin quantum number, i.e. +1/2.

When carbon atom combines with hydrogen atom, the simple molecule that can be formed is methane, CH4. Each C atom bonds with 4 H atoms. This is an unusual bond, because C atom only has two single electrons, so it must be 2 H atoms are bonded with each C atom. However, if C atom only bonds with 2 H atoms, the outer shell of C atom only contains 6 electrons. The rule for achieving stability of electrons are duplet (2 electrons filled) or octet (8 electrons filled). This evident that there is a special bond and an unusual bond, is called HYBRIDIZATION which has been mentioned above.

An rearrangement of electrons is occurred from the ground state, 1s2 2s2 2px1 2py1 2pz0 becomes 1s2 2s1 2px1 2py1 2pz1. One electron from 2s1 moves to 2pz1, so after the electron promotes, C atom has 4 unpairs electrons in the four orbitals. This condition, we called in the excited state. Immediately, almost at the same time, there is an energy transfer from the electrons in the 2p orbitals to the electron in 2s orbital. The four orbitals 2s,. 2px, 2py, and 2pz have the same energy level. This evident is called a hybridization. Because there are one s orbital and three p orbitals change, each orbital named as sp3 orbital. Now, there are 4 hybrid orbitals, e.i. sp3 hybrid orbitals.

Be careful, the hybridization concept is a hypothetical concept, so don't use hybridization to predict the shape of molecules or ions. The geometry should be known first, and you can predict its hybridization.

Hybridization can be sp, sp2, sp3, dsp2, etc. Apply this concept to other examples, then you can learn other type of hybridization.

THE TYPE OF MOLECULAR GEOMETRY

See the table above, relate the type of molecules, shape of molecules, electron arrangements of bond pair (BP) and lone pair (LP), molecular geometry, and the examples of each type. There are two different colors in the molecular models, white colors are the atoms bonded to the central atom (red color), yellow colors are lone pair (LP) electrons of the central atom.

From the examples, you can arrange both BP and LP electrons and the molecular geometry by using real atoms.

THE AXE SYSTEM

The general formula of molecular geometry uses the AXE system. A is the central atom, X is ligands (atoms around A and bonded to A), E is(are) lone pair (LP) of electrons around A.

GEOMETRY OF WATER

After you learnt molecular geometry of methane and ammonia, make paragraphs to explain geometry of water, including comparison of water with methane and ammonia.

Please explain both pictures. For the first picture, explain according to the order of the picture. Similarly, explain the second picture.
Don't forget to compare geometry of the 3 compounds. For doing this, you can draw all the 3 compounds.

ELECTRON PAIR GEOMETRY AND MOLECULAR GEOMETRY

The electron pair geometry of methane and ammonia is tetrahedral. Both have four pairs of electrons around the central atom (C and N). In methane, C has four bonds (4 BP). In ammonia, N has 3 bonds (3 BP) and one lone pair of electrons (1 LP).
Electron pair geometry is determined by the number of electrons around the central atom, both bond pairs (BP) and lone pairs (LP). These geometry is a domain electrons postulated by VSEPR.
This domain is as a result of minimizing the repulsions between electron pairs. Remember, in the VSEPR theory, the repulsion of BP - BP < BP - LP < LP - LP. In practise, the balloon for LP is bigger than BP, because the repulsion of LP is stronger than BP.
Because methane has 4 BP, the strength of repulsion is the same, its molecular geometry is also tetrahedral, as same as its electron pair geometry. Ammonia has 3BP and 1 LP, the repulsion of LP - BP > BP - BP. That is why, its molecular geometry is trigonal pyramidal. So the molecular geometry differs with its electron pair geometry. Please think about water molecule and compare its geometry with methane and ammonia.

RADIUS OF ATOMS AND IONS

Hallo everybody, this moment we discuss about radius of atoms and ions.

Your task is finding keywords rather than writing paragraphs. Look at the picture, why does the radius of cation is smaller than its atom? Okay, this is a clue for you. To find keywords, you have to make questions, answer these questions. Ask something by using the words what, how, and why. Then from your answers, hopefully you can find a lot of keywords. Don't forget to think about electron configurations, inner shell, outer shell, orbitals, valence electrons, the position of elements in the periodic table, ionisation energy, etc. Use the value of atomic and ionic radii.

HYDROGEN MOLECULES

A hydrogen atom only has one electron, so it only has one s sub shell, that is 1s orbital.
Hydrogen atom is not stable. It can stable if it has 2 electrons (duplet rule). That is why, hydrogen gas consist of 2 atoms per molecule (diatomic molecule). When two hydrogen atoms are closely, the electrons are attracted by each hydrogen's protons, and share one of another to form an electron pair. As a result, there is a non polar covalent bond of hydrogen molecule, H2. The non polar bond is occurred, because these two hydrogen atoms have the same ability of attraction.

ORBITALS PROBLEMS

Students, do you still open my blog? Of course, if you want to be the best student, so spend your time to learn something in this long holiday.
Do you remember these orbitals?
These orbitals are very important for elements in the A (main) groups.
1. How many orbital(s) is (are) in the s sub shell?
2. How many orbitals are in the p sub shells?
3. Do you remember, how many sub shells are maximum in an atom?
4. There are atoms that only have a s orbital. Whose are these elements?
5. Write the electron configuration of those elements.
6. There are 18 elements whose have s and p orbitals. Write the electron configuration of these elements.
7. What is the difference between px, py and pz orbitals?
8. What is the difference between 1s and 2s orbitals?

IONIC COMPOUNDS PROBLEMS

This task is about writing the chemical formulas of ionic compounds.
the numbers above periodic table at each group are the oxidation number of atom in their compounds. Remember, if the atom an element, the oxidation number is zero.
For ionic compounds, the oxidation number is the charge of the cations and anions.
Covalent compounds consist of atoms rather than ions, because there is an electron shared. The oxidation number indicated the number of electron shared (bonded electron pairs, BP). The minus sign indicates that the BP electrons is closely to the atom which has greater electronegativity. This discussing only focuses on the ionic compounds.
1. Write formula of compound between berilium and fluorine.
2. Find 10 (ten) formulas of ionic compounds.
3. Predict which compound from no. (2) has highest boiling point and give the reason.
4. Predict which compound has lowest boiling point and give the reason.

EXCITED STATE OF ELECTRON

Students, I want to remind you about an electron in the ground state and excited state.
An electron of an atom, from the ground state position can move to the high energy level, if there is an absorption of photon. The energy of this electron will increase and energy level will also increase, higher than before. This electron move to the high energy level, the next level. In this new position, we call as an excited state. However, this electron is not stable, because the energy immediately release from the electron. At the same time, this electron go back to the initial level, that is the ground state position. The energy changes become a spectrum.

ELECTRON SHELLS

Students, do you remember about electron shells from Bohr atomic theory?
Okay, we discuss now. The picture shows electron shells of some elements that outer shells are not filled.
There is a possibility of these elements react with other elements, because they are not stable.
For stability, the number of electrons in the outer shell should be 2 electrons if it is closely to the helium atom (duplet rule) and 8 electrons if it is closely to the other inert gases (octet rule).


Look at a sodium atom. There is an electron in the outer shell, so if it reacts with a chlorine atom, it will loose the outer electron and it will form sodium ion, Na+. A chlorine atom, Cl will gain electron and form Cl- ion which has 8 electrons in the outer shell. Now Na+ is also has 8 electron in the outer shell (from the inner shell ). Both Na+ and Cl- now become stable. These ions attract one of another; as a result, these form NaCl(s) as a crystal. Na and Cl are chemically reactive.

HYDROGEN BONDING

Water consists of polar molecules and these molecules attract each other as shown in the picture. This attraction is named hydrogen bond as the strongest intermolecular force.
Remember the intermolecular forces between HCl molecules. Why does the force between H2O molecules is stronger than HCl molecules?
You have to think the electronegativity of O and Cl. The electronegativity of oxygen atom is greater than chlorine atom, so that H2O molecules are more polar than HCl molecules.
How about fluor and nitrogen atoms? Electronegativity of Fluor atom is greater than oxygen atom and oxygen atom is greater than nitrogen atom. EN F> O > N. Are these elements have a hydrogen bonding in their compounds with hydrogen atoms? Certainly yes, they are. Because all these elements have the greatest electronegativity. Please think about HF and NH3, and alcohol molecules.

AQUEOUS SOLUTION

Aqueous Solution of NaCl(aq)

Dissolving table salt, NaCl(s) into water, H2O.

You see that a crystal of NaCl(s) consists of cation, Na+ and anion, Cl-. During dissolving, one by one Na+ and Cl- are separated from the crystal, mix with water molecules.

Water molecule is a polar solvent and as a solute, salt is an ionic compound, so water has an ability to dissolve salt. This is because water and salt have a similar property, that is both have a charge. The charge of salt is come from the ions, cations and anions, and the charge of water is from its dipoles, positive poles and negative poles.

As you see from the picture, water molecules have a job to attract Na+ and Cl- from the salt. One by one, each ion is surrounded by water molecules, in another word, water molecules cover the salt ion. This process called SOLVATION. Na+ is surrounded by H2O with the negative poles (oxygen) are closely to the Na+. Cl- is surrounded by H2O with the positive poles are closely to the Cl-.

If there are a few of solute, so a lot of water molecules cover each ion of salt. The degree of dissociation of salt is 100%. Its mean, all salt can dissolve into water.

If there are a lot of solute, so water molecules are not enough to cover the salt ions. The salt ion cannot cover completely with water molecules. Because of this, Na+(aq) and Cl-(aq) can attract each other. This process called POLARIZATION. The degree of dissociation of salt is less than 100%.

Salt is a strong electrolyte, however, if the solution is too concentrated, there is a polarization.

PERIODIC TABLE OF ELEMENTS

Here is a small periodic table that you can copy and make it in a hard paper or cartoon, so you can bring it everywhere and everyday. When you are free, spend a time to look at this table. Hopefully, day by day you can understand in dept the periodic properties of the important elements. I don't say that you must remember the symbol of elements. I mean, please think that the order of the elements both in a group and in a period, indicate a periodical properties, show the similarities and differences among the elements. All of these you have learnt in the X class this semester (first semester).
You can make more than one copy, yeah ... it like a card, an ID card. Remember, this card is the key of chemistry.

FIRST IONIZATION ENERGY

Do you remember what is first ionization energy? For example Ca in the IIA group has 2 valence electrons. When it reacts with fluorine, VIIA group, Ca will loose 2 electrons and each F atom will gain an electron, that is why the empirical formula of this compound is CaF2.

However, Ca doesn't loose the 2 valence electrons directly, but one by one. The energy needed to loose the weakest electron is named first ionization energy, and the other one is called second ionization energy.

Which one harder than the other in loosing electron, Ca atom or Ca+ ion? Is it correct that the harder one is the second? What is the reason? Okay, think carefully and keep your best thought.

ATOMIC RADIUS GRAPH

Here atomic radius graphs of elements in the periodic table.

Think about it. Compare with atomic radius that you have explained before.

Okay, read the graph and draw a conclusion please.

PERIODIC PROPERTIES TASK

Now focus your writing on the periodic properties as shown in the diagram.
Please use your logical thinking in doing this. Firstly what do you want to explain; secondly ...; and what will you do next. Then finally ....
If you don't know the order, its okay, just explain one by one; and then please think about the relationship between the properties you have explained. Think about cause and effect; so you will realise which one come first.
The paragraphs you have to write is about 250 words. Is it okay?

ELECTRONEGATIVITY TASK

This is another periodic property of elements in the periodic table.
What is the meaning of electronegativity?
Why the arrow of increasing electronegativity is different with increasing atomic radius?
So your task is, write paragraphs about 2oo words to clarify these periodic properties of elements. Don't forget to include explanation which element is the most electropositive one and which element is most electronegative. What the effect of these properties are.

ATOMIC RADIUS

Hi Students, what are you doing? Its Okay, I am sure that you can manage your time.

I want to remind you, in learning chemistry, Periodic Table is the Key. Certainly, the periodic properties of the elements are a fundamental concept that you have to use in thinking chemical bonding, chemical reaction, and other concepts. In learning chemistry you have to think logically and creatively. Do you remember why increasing atomic radius follows the arrow shown in the diagram above? Don't forget the reason, please.

ATTRACTION AND REPULSION IN IONIC BOND

Students, do you remember that in the ionic compound, cations and anions attract one of another. This attraction is the main effect in the ionic bonding.
Na(2,8,1) + IE --> Na+(2,8) + 1e
Cl(2,8,7) +1e --> Cl-(2,8,8) + EA
However, there is a slightly repulsion of the inner electrons of Na+ and outer electrons of Cl-.
Attraction of different charges and repulsion of electrons are occured among all Na+ ions and all Cl- ions, then they are closely together and form a cristall. The ratio of Na+ and Cl- = 1 : 1. The chemical formula of this compound is named emphirical formula, that is NaCl.
When barium ions, Ba2+ combine with Cl- ions, the formula is BaCl2, because the ratio of Ba2+ and Cl- = 1 : 2. Ba2+ + 2Cl- --> BaCl2.

MOLECULAR SHAPES TASK

To predict molecular shape, the VSEPR theory (Valence Shells Electron Pairs Repulsion) can help us. Use balloon for simple prediction of molecular shapes.
Make 3 dimension shapes, if possible use different balloon for different atom. Firstly you can make a linear shape. Please give an example of each shape. For example : hydrogen molecule, H2 is linear. Make a table to show each molecule has certain shape. Complete your table with Lewis structure, determine bonding pair (BP) and lone pair (LP) electrons. Firstly think about symmetrical shapes, then unsymmetrical shapes. Mention about their molecular polarities, polar or non polar molecules.

WATER BUBLES

Water .. water .. water. The is everywhere in the world. The role of water is realy very important in our life. Okay now, again we discuss about water.
Sometimes, when we look at a glass of water, there are bubles in the water. What do the bubles? Where are the bubles come from?
If we discuss about pure water, so the glass only consists of water molecules. In this water, sometimes we see bubles. These bubles are water molecules. This is happening, because there is an amount of energy from the environment arround water, absorped by water molecules. The kinetic energy of these molecules are greater than before, they move faster than the others. That is why, there are bubles, because these molecules make holes in the water for their movement. These molecules, at that time, change into a gasous state.
We can conclude that the bubles are water gas in the water liquid. this evident will disappear when the kinetic energy of molecules changes into their basic condition. The water gas changes into water liquid. However, the bubles will appear again sometimes if there is an energy transferred from environment to the system.

WATER COVALENT BONDING TASK

This is another example of polar covalent bond. Write an explanation text about 150 words, around 3 - 4 paragraphs.

You have to choose the best sentences which have a full meaning and short. Don't make it to long, because you will loose the relationship between concepts.

The paragraphs move from general to the specific concepts, from concreate to abstract theories.
Please try, you have to develop your writing step by step gradually, OK? So do it.

POLAR COVALENT BONDING TASK

Students, develop your thinking to the next bonding, that is polar covalent, as seen in the picture.
Before explaining this bond, firstly distinguish between polar and non polar covalent bonds. It is about polarity of bonding. The bond of H2 and Cl2 are different with the bond of HCl. The first are molecules of elements, on the other hand, the last is a molecular compound.
In writing the paragraphs, mention about electronegativity, the position of bonding electron pair (BP) between H - Cl, and the effect of this BP.

OXYGEN MOLECULES TASK

The next concept is the bond of oxygen molecules. Paragraphs that you have to write consist of Lewis structure, octet rule, non polar covalent bond, and double bond.
Firstly concern with oxygen molecules, then draw a conclusion.
After that, move on another example of non polar bond, such as nitrogen. Be careful, remember that valence electron of nitrogen atom is different with oxygen atom, so the type of non polar bond is also different.
Draw a diagram of nitrogen, similar to the diagram of oxygen in the picture.

NON POLAR COVALENT BONDING TASK

After you learn quite a lot about an ionic bond, now think another bond, that is a covalent bond.
Look at the picture, the simplest example is a hydrogen molecule. Compare this bond with ionic bond, such as in table salt, NaCl.
Is there any electron transfer in the bond between hydrogen atoms? Are you sure there is no electron transfer at all? What is the reason? Hydrogen is a non metal, so the bond is really different with NaCl, because sodium is a metal. Its OK, good point.
As before, your task is, make paragraphs which consist of clear explanation about the bond oh H2 molecules. Don't forget to mention Lewis structure, duplet rule, single covalent bond, and non polar covalent bond, including the reason of each clarification. Then apply this concept to another similar molecule, such as chlorine molecules.

RUST FORMATION TASK

Similarly, do this task based on the diagram, as same as the previous task about ionic compounds.
This is the process of rusting that is very often occurred in the daily life.
Be careful, although iron is a metal from the VIIIB group, its oxidation number are +2 and +3.
So that, don't draw all valence electrons of iron, just the number of electrons used in the process.
Draw a conclusion after finishing your explanation.

IONIC COMPOUNDS' FORMATION TASK

After you think about positive ions and negative ions, now combine these to different ions in forming an ionic compound. Firstly, use your ions, both fluoride and sodium. Your cognitive should be developed step by step following the diagram. It is very important, because it will help you understand the concepts in dept.

You have to explain, for example, when a metal of IA group and a non metal of VIIA group meet, they will ....

Continue to explain another metal and another non metal from the same group with the above, make a diagram first, then paragraphs.

POSITIVE IONS TASK

Students, similar to your task about negative ions, make paragraphs according to this diagram.

After that, develop your explanation to compare alkaline metals, focus on lithium, sodium, and potassium.

Remember, your comparison including radius of atoms, ions, and find an isoelectronic.

One more concept needs to be discussed, why the picture tell us about Bohr Diagram?

NEGATIVE IONS TASK

Write paragraphs to explain this picture. As you see, this is about the formation of fluoride negative ion. I hope your explanation including a description about the reason why it relates with neon atom, octet's rule, the charge is - 1. Explain about isoelectronic, comparing radius of fluoride ion and its atom, radius of both atoms,fluorine and neon.
Similar to the above explanation, develop your concepts to compare halogen elements, from fluorine to iodine. OK, please keep learning with always relax, serious, and success.

LABORATORY ACTIVITY TASK

Explain what is happening according to this picture. You can directly write paragraphs, or you will classify your description into several topics, its OK, however, you have to include some essential concepts that should be explained. Do that immediately, every cancelling something, you will cancel so many things, you don't realize that, please, learn from your past experiences. Good luck.

BOILING POINT OF WATER

When you boil liquid water, it will change to the gaseous state. Explain clearly step by step, from the first till the final. For example, you start from explaining water at room temperature is a liquid. This means that water molecules ..., so this molecule ... one of another; etc. Explain when you heat water, the molecules .... You can classify: before heating, during heating till boil, after boiling point. OK, do the best.

PH OF ACID SOLUTION TASK

There are two solutions, red and yellow colors. These colors come from the indicator used in these different solutions. The pH value of both are different, the pH of the red color is lower than the pH of the other one.
The equipment is called a pH meter.
Make a plan for doing this and write down the data from the above observation. In the report, write the solution you use. There are two set of solutions, first from the calculation of concentration, use HCl(aq) and the other set, use solution from the kitchen.

YELLOW - BLUE SOLUTION TASK

Predict the 3 solutions that have different value of pH.
Before predicting these solutions, think about the indicator used in these solutions. What the reason that make the indicator has different color in different solution.
Don't forget to find examples of each solution.

PRECIPITATION REACTION TASK

Predict what is that in the beaker glass? If you do this experiment, explain what solution is firstly in the beaker and what solution is in the pipete that you have dropped?

I give you an important information.

If the yellow precipitation is :

1. plumbum(II) iodide or

2. silver(I) iodide

Write down the two chemical equations based on the information above. Try to write two different equations for each reaction; that are a molecular equation and an ionic equation.

CHEMICAL REACTION TASK

Find reactions that need heating to make the substances react. Use your textbook, or open the important links in my blog to find students' resources. Focus on the type of reaction.

The possible substances are elements or compounds; and these substances can be solid, solid and solution, solution and solution.

Explain the reactions clearly.

The explanation includes chemical equation, description of the reaction, the reason why certain reaction needs heating.

ACID - BASE TASK

Students, think about this picture. Please predict, what is that? There is a word "DESTROY" . This word is likely very important in this evident.

OK, this is your task in this holiday. Keep learning and enjoy doing something that can develop your knowledge continuously.

Make parahraphs by using the evident showed in the picture. Don't forget to give a title of your article.

If you have a blog, please publish your article and you can follow my blog.

CORROSION

This is a result of an experiment did by a group of students. Please think about this. This data is about corrosion of iron. The red color indicates a base solution. The middle of no. (c) there is a white precipitation of a hydroxide, around a certain metal that covers the iron.

OK, your task are:

1. Predict all the data

2. Make a report

3. Make paragraph about corrosion of iron.

LEMON SHELL GAME

What is she doing with the lemon. Help she to make the plan and make a report of this observation. Your report should be included title, propose, prediction, equipments, substances, table for recording data, discussion, and conclusion.
You can also make a suggestion for doing another reaction similar with this by using other materials in the kitchen.
Suggest an experiment in the chemistry laboratory, concerns with this type of reaction.
Finally, think about this type of reaction and make a description about this.