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

(i)
               
(ii) Excess Zinc carbonate is used to make sure that all the hydrochloric acid are completely neutralised.

(iii) Firstly, fliter out the excess zinc carbonate from the solution and the zinc chloride solution will be left.Zince chloride crystals can be obtained by evaporating the Zinc chloride salution to saturated and allow the sartuated zinc chloride solution to cool down. Crystals of zinc chloride will be formed.

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

(i) Potassium sulfate is a Group(I) soluble salt. Titration is recommended for preparation of all Group (I) salts as they are soluble. As the solutions used are colourless, indicatior is also used to identify the end point of neutralization between sulfuric acid (colourless) and potassium hydroxide (colourless) where the solution with indicator turns colourless.

(ii)
   

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

(i) The gas produced is Ammonia.

(ii) Anion: Nitrate ions (NO3-).

(iii) Cation: Iron (II) (Fe2+)

Q2 Ammonium sulfate is heated with sodium hydroxide

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

(ii) Ammonia produced will turn damp red litmus paper to blue.

Prepare for EYE : 5 Questions on Ionic Equations, Colours of Cations & Anions, Acids, Bases, Alkalis, Salts

Q1.(i) Zinc Nitrate+Aqueous ammonia --> Zinc hydroxide + Ammonium Nitrate
Thus, the salt formed is ammonium nitrate while the base for is zinc hydroxide.

(ii) Observation of reaction: When Ammonium hydroxide(colourless solution) is added to Zinc nitrate(also colourless solution), white precipitates formed as Zinc Hydroxide is insoluble.

(iii)   Zn(NO3)2 (aq) + 2NH4OH (aq) --> Zn(OH)2 (s)+ 2NH4NO3 (aq)

 (iv)