In the following schematic diagram for the preparation of hydrogen gas as shown in Figure, what would happen if following changes are made?
(a) In place of Zn granules , same amount of zinc dust is taken in the test tube
(b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken
(c) In place of Zn, Cu turnings are taken
(d) Sodium hydroxide is taken in place of sulphuric acid and tube is heated
OR
A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identity X, Y, G and Z. Also, write the chemical reactions involved.
(a) If Zinc dust is used in place of zinc granules, then the same reaction will occur and hydrogen gas is evolved. But the reaction rate will increase due to the increase in surface area of reactants.
(b) If dilute hydrochloric acid is taken in place of dilute sulphuric acid, then Zinc Chloride (ZnCl2) is formed in place of Zinc Sulphate (ZnSO4) as follows:
Zn + 2HCl → ZnCl2 + H2O
(c) If Copper turnings are used in place of Zinc granules, then no reaction will take place because copper does not react with dilute acids under normal conditions due to its lower reactivity than Zinc.
NOTE: Copper lies at a lower position than Zinc in electrochemical series. Hence, it it less reactive than Zinc.
(d) If Sodium hydroxide (NaOH) is taken in place of Sulphuric acid (H2SO4), then Sodium Zincate is formed as a product. The reaction is as follows:
Zn + 2NaOH → Na2ZnO2 + H2
Heating the test tube will increase the rate of the reaction due to an increase in supply of heat energy.
OR
X is Calcium carbonate (CaCO3). Y is slaked lime [Ca(OH)2]. G is chlorine (Cl2) gas. Z is bleaching powder (CaOCl2).
CaCO3 on reacting with HCl (an acid) gives CO2 gas as follows:
CaCO3 + 2HCl → CaCl2 + CO2 + H2O
When CO2 is passed through lime water, it gives CaCO3 back as follows:
CO2 + Ca(OH)2 → CaCO3 + H2O
When Cl2 gas, which is obtained at anode on electrolysis of brine, is passed on dry slaked lime [Ca(OH)2], it gives bleaching powder (CaOCl2) as follows:
Cl2 + Ca(OH)2 (dry) → CaOCl2 + H2O