フィクション

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. The base is Ammonium Nitrate .

ii) Describe the observations for the reaction.

When Zinc Nitrate and aqueous ammonia react with one another, a white precipitate will be formed.

(iii) Write a chemical equation for the reaction (include state symbols).

ZnNO3(aq) + 2NH4OH (aq) > Zn(OH)2 (s) + 2NH4NO3 (aq)

(iv) Write an ionic equation for the reaction.

Zn 2+ (aq) + OH- (aq) > Zn(OH)2 (s)

Q2 Ammonium sulfate is heated with sodium hydroxide.

(i) Write a chemical equation (include state symbols) for the reaction.

(NH4)2 SO4 (aq) + 2NaOH > Na2 SO4 (aq) + 2H2O (i) +2 NH3 (g)

(ii) Describe a test for the gas.

It turns damp red litmus paper blue.

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

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

Nitrate

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

Iron (II)

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.

It is soluble Group I salt and hence by using titration method, we will be able to get the salt.

(ii) Write an ionic equation for the reaction.

H+ (aq) + OH- (aq) > H2O (L)

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

(i) Write an ionic equation for the reaction.

ZnCO3 (s) + H+ (aq) > Zn+ (aq) + H2O(L) + CO2(g)

(ii) Why excess zinc carbonate is used?

It is used to ensure that zinc carbonate and hydrochloric acid is fully reacted.

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

As there is excess black zinc carbonate solid left , filter to remove the excess unreacted and evaporate it to form a saturated salt solution. The hot saturated solution will then form zinc chloride crystals when it is being cooled down.

Photos!

Here! This are all the photos! (:

Comments

Here are the 3 Comments (:

1. Aleen Tan (27)

I like the way she asnwered all the questions in the blog. The answers were detailed and well-explained. She stated clearly on what is what and besides that, she put in extra effort in finding the pictures that are relevant to the questions and she actually shared all her knowledge of this chapter in the blog.I like that for qns 5, besides saying Group 1, 2 and 3 are metals, she also added metals from other groups that is not from group 1,2 and 3 to make it more detailed. She never fails to put in examples and even though her answers were long, it was easy to understand. One mistake was that the charge outside should be + and not 1+. For her blog, it's very simple and i like it. She shared with us her achievements, favourites, hobby and hates and i'm sure she puts in alot of effort in it. In short, You did a great great great Job! :D

2. Wan Ling (16)

I like that her answes were short, sweet and simple. Even though it was short, all the information was inside. I like that she includes pictures for almost all the questions to make her answer seem more interesting. One mistake was that is should be 1/1840 and not 1/1836. For her blog, her ownership for her blog is excellent as besides posting pictures and photos of her, she also posted videos that she likes from the internet! All the videos and photos she posted was interesting and i think we should learn from her. Overall, Well Done! ^.^

3. Xue Li (7)

I like that she had included pictures for almost all the questions but then, we should always put acknowledgement so please remember to put in order so that marks will not be deducted. You have also forgotten to put the drawings for sulfide ion to answer the questions. All points were included in the answers and i think nothing was left out, which is good. The blog is simple and it seems that she actually put in effort in doing the blog, for she also added in music. Anw, Good job!(:

Done!

Okay, Chemistry Blog is done.! Done the blog is up to standard! 7 July is coming, which means its my DaJie's birthday (:

Fifth Question (:

5. Sodium is a metal and sulfur is a non-metal....why we classify them this way??

Sodium is a metal as it has a valance electron of 1 that will be lost during a chemical reaction to make it stable and when it lost electron, it is positively charge. For sulfur it is a non-metal , it has a valance electron of 6 and it will gain 2 electrons during a chemical reaction to make it stable. As it gain electrons, it becomes negatively charge. In the Periodic Table, Sodium is being classified in Group (I) and they are metals. On the other hand, for Sulfur, it is being classified under Group (IV) which are non-metals. Therefore Sodium is able to conduct electricity as it is a metal and sulfur does not conduct electricity as it is a non-metal.

Fourth Question (:

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

Isotopes are different atoms of the same element which have the same number of protons but different number of neutrons.

Isotopes	Mass Number	neutrons	Atomic Number	protons	electrons	Electronic structure	Valence electrons
chlorine 35	35	18	17	17	17	2.8.7	7
chlorine 37	37	20	17	17	17	2.8.7	7

They have the same number of protons that is 17 but they do not have the same number of neutrons as chlorine 35 has 18 neutrons and chlorine 37 has 20 neutrons. As they both have the same number of protons but different number of neutrons, we can hence conclude that they are isotopes.

taken from http://alexteoh.com/Atomic%20Structure.htm

Third Question (:

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

In the above photo, it shows sulfur atom and sulfide ion. In sulfur atom, it has an electronic configuration of (2.8.6). This means that it is not stable as the valance shell only has 6 electrons and to make it stable, it must have 8 electrons. Therefore, in order to make it stable, it needs to gain 2 more electrons to make it 8 electrons to be stable. When it gain 2 electrons, the electronic configuration becomes (2.8.8) and it becomes a sulfide ion. As the overall is negatively charge, it is S2-.

Info

Agnes, Fifteen, YHSS, 3E5 , YHCB; String Bass <3. Currently residing in Singapore, (: . I enjoy CHEMISTRY. :D
Facebook Twitter

Credits

Blogskin made by Gabby with header image from flickr.