comments on friends!!

On Shuyu(12)- I think she put in a lot effort doing it! Her answers are very clear and easy to understand, she even take the effort to make a range of colours for the questions and answers which make it even neater and easy to read. But i think it would be better if she show the working of how she obtain the ionic equations

On Cindy(02)- great effort as well!! I like her way of answering the question it make me understand more. It is really a good idea to write the ionic equation on the paper and scan into the computer, i actually learn from her XD her picture are very clear and neat, she show the working too which is very good. Her answer is very detail as well like for q1(ii) she mention that "a colourless soluble salt ammonium nitrate", very few people mention about this point which i think is very important too.

On Jieen(13)- She put in effort doing it too! nice answer!! Her answers are clear-cut and easy to understand. Like what i mentioned earlier i think it would be better if she show the working of how she obtain the ionic equations. For q4(i) many people only write one sentence and give a brief explaination but her answer is very detail and useful!

To conclude, i think all three of them really spend time and effort doing it, i couldn't manage to find only mistake so very well done!!! :)

Q1 Zinc nitrate reacts with aqueous ammonia (NH4OH) to form a salt and a base.
(i) Name the salt and the base.
The salt is zinc hydroxide Zn(OH)2 . The base is Ammonium Nitrate NH4NO3.

(ii) Describe the observations for the reaction.
A white precipitate of zinc hydroxide Zn(OH)2 is formed.

(iii) Write a chemical equation for the reaction.
Zn(NO)3(aq) + 2NH4OH(aq) --> Zn(OH)2(s) + 2NH4NO3(aq)

(iv) Write an ionic equation for the reaction.

Q2 Ammonium sulfate is heated with sodium hydroxide.

(i)Write a chemical equation for the reaction.

(NH4)2SO4 (aq) + 2NaOH (aq) -> Na2SO4 (s) + 2NH3 (g) + 2H2O (l)

(ii) Describe a test for the gas.

Ammonia gas will turn red damp litmus paper to blue in colour.

Q3 An unknown green solution is heated with a piece of aluminium foil and sodium hydroxide solution.

(i) The gas produced turns damp red litmus paper blue. Name the gas evolved.

Ammonia gas

(ii) This is a confirmatory test for an anion. Name this anion.

The anion is Nitrate (NO3-)

(iii) Give a possible cation which gives the green solution.

The possible cation is Iron(III) Fe2+.

Q4 Sulfuric acid is titrated with potassium hydroxide in the preparation of potassium sulfate salt.

(i) Explain why this method is recommended for the preparation for this salt.

Potassium sulfate is a group (I) salt and is soluble.

(ii) Write an ionic equation for the reaction.

Q5 Excess zinc carbonate is added to hydrochloric acid in the preparation of zinc chloride salt.

(i)Write an ionic equation for the reaction

(ii)Why excess zinc carbonate is used?

It is used to ensure that all the hydrochloric acid is completely reacted with the zinc carbonate.

(iii) Briefly explain how the zinc chloride crystals can be obtained.

Step 1: Add excess zinc carbonate solid to beaker of dilute hydrochloric acid until there is excess white zinc carbonate solid left behind.

Step 2: filter to remove the excess unreacted zinc carbonate solid.

Step 3: evaporate the zinc chloride solution to remove water and make a saturated salt solution.

Step 4: the hot saturated solution form zinc chloride salt when it is cooled.

Comments on friends!! :)

On Cindy(02)-great effort! the points are very detail and image are very clear and easy to understand too! I think it is very good to highlight the keywords, i should also do so the next time round! For question 2 and 3 she even include the point that "losing 6 electron is difficult...& gaining 7 elecrons is difficult... respectively.", which very few people do so. I think it is good that she include this point which make us understand even clearer. The blogskin is very nice! you link up the people, i should do so soon!


On janis(09)-She put in effort doing it too! information detail as well, pictures are very clear and useful! It is good that she search for images, however she should acknowledge the source next time round. For question 2, i think she never include the blacket and put(+) charge. For question 3,she should also include the atomic structure of sulfur atom and sulfide ion, it should be sulfide ion instead of sulfur ion. I think maybe next time font can be more clearer and bigger so it will be easier to read! To conclude, she did well too!


On Jieen(13)-great effort as well! nice answer! it is easy to understand and pictures are very clear too! i have difficulties finding her mistake. i think the words can be bigger next time so it will be easier to read! nice and peaceful song that make me feel like continue reading your blog! is good that you link up the people too!

A wonderful day at jurong central park!

See i am the tallest!! :) love them all!<3

1. What does an atom looks like? What are the sub-atomic particles inside it?

The atom is the smallest foundation unit or particle of an element that can exist. Atoms are made up of 3 types of particles electrons, protons and neutrons. These particles have different properties. Electrons are tiny and light particles that have a negative electrical charge (-). Protons are much larger and heavier than electrons and have a positive charge (+). Neutrons are large and heavy like protons; however neutrons have no electrical charge. Each atom is made up of a combination of these particles. Atoms are neutral because all the no. of protons are equal to the no. of electrons.

The centre of an atom is known as a nucleus. Protons and neutrons are the subatomic particles found inside the nucleus.

Each shell can contain only a fixed number of electrons. The first shell can only hold 2 electrons while the second and third shell can only hold 8 electrons.

2.Draw the atomic structure of a sodium atom and a sodium ion....explain why you draw it this way.

Sodium atom (2.8.1) is a metal because it loss 1 electron to become sodium ion to complete the valance shells to make it stable.

3. Draw the atomic structure of a sulfur atom and a sulfide ion....explain why you draw it this way.

Sulfide atom (2.8.6) is a non-metal because it will gain 2 electrons to become sulfide ion to complete the whole shell, to make it stable.

4. Chlorine-35 atom and Chlorine-37 atom are called isotopes...Use these two examples to explain what is 'isotopes'.

Different atoms of the same element which have the same number of protons but different number of neutrons, is known as isotopes.
Chloride-35 have 17 protons and (35−17=) 18 neutrons. While chloride-37 have 17 protons and (37−17=) 20 neutrons. They have the same number of protons (17p) but different number of neutrons (18 and 20 respectively). Therefore they are isotopes.

5. Sodium is a metal and sulfur is a non-metal....why we classify them this way??
Sodium (2.8.1) is a metal because it loss 1 electron to complete the valance shells to make it stable and it is in group (I). While sulfur (2.8.6) is a non-metal because it will gain 2 electrons to complete the whole shell to make it stable and it is in group (VI).
In the periodic table, Metals are generally in the groups(I),(II),(III) while non-metals are generally in the groups(IV),(V),(VI),(VII),(VIII).