1. Zinc nitrate reacts with aqueous ammonia (NH4OH) to form a salt and a base.
(i) Name the salt and the base.
(ii) Describe the observations for the reaction.
(iii) Write a chemical equation for the reaction (include state symbols).
(iv) Write an ionic equation for the reaction.

(i) The salt is ammonia nitrate and the base is zinc hydroxide.
(ii) Aqueous ammonia and zinc nitrate are aqueous solutions mixed together. After the reaction, a solid precipitate (ammonia nitrate) and an aqueous solution (zinc hydroxide) is formed.
(iii) Zn(NO3)2 (aq)   +   2NH4OH (aq)   =   2NH4NO3 (aq)   +   Zn(OH)2 (s)
(iv) Zn2+ (aq)   +   2OH- (aq)   =   Zn(OH)2 (s)


2. Ammonium sulfate is heated with sodium hydroxide.
(i) Write a chemical equation (include state symbols) for the reaction.
(ii)  Describe a test for the gas.

(i) (NH4)2SO4 (aq)   +   2NaOH (aq)   =   Na2SO4 (aq)   +   2H2O (l)   +   2NH3 (g)
(ii) The gas (ammonia gas) will turn damp red litmus paper blue.


3. 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.
(ii) This is a confirmatory test for an anion. Name this anion.
(iii) Give a possible cation which gives the green solution.

(i) Ammonia gas.
(ii) Ammonium hydroxide.
(iii) Iron(II).


4. 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.
(ii) Write an ionic equation for the reaction.

(i) Potassium sulfate is a Group(I) soluble salt. Therefore, titration is the best way to prepare this salt.
(ii) OH- (aq)   +   H+ (aq)   =   H2O (l)


5. 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?
(iii) Briefly explain how the zinc chloride crystals can be obtained.

(i) (CO3)2- (aq)   +   2H+ (aq)   =   H2O (l)   +   CO2 (g)
(ii) It is because the salt (zinc chloride) is a transition metal souble salt. Therefore, the method to prepare this type of salt is excess solid + acid method. Zinc carbonate is a solid, so hence, it is used.
(iii)  Add the excess zinc carbonate to a beaker of hydrochloric acid, until it cannot react anymore and leaves the zinc carbonate unreacted. Heat the acid while doing so. Next, when there is excess zinc carbonate, filter it to remove the unreacted solid. Evaporate the filtrate to form a saturated salt solution. The saturated solution will form zinc chloride crystals upon cooling.