question_answer

        (i) In the following schematic diagram for the preparation of hydrogen gas as shown in shown in figure, what would happen if following changes are made (a) In place of zinc granules, same amount of zinc dust is taken in the test tube. (b)Instead of dilute sulphuric acid, dilute hydrochloric acid is taken. (c)Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated. (ii) How do metal carbonates and metal hydrogen carbonates react with acids?                                        [NCERT Exemplar]

Answer:

                   (i) (a) Hydrogen gas will evolve with greater speed. (b) Almost same amount of gas is evolved. (c) If sodium hydroxide is taken, hydrogen gas will be evolved. (ii) All metal carbonates and hydrogen carbonates react with acids to form a corresponding salt, carbon dioxide and water. Metal carbonate + Acid ® Salt + Carbon dioxide + Water Metal hydrogen carbonate + Acid ®Salt + Carbon dioxide + Water For example, sodium carbonate reacts with dilute hydrochloric acid as follows: Sodium hydrogen carbonate reacts with dilute hydrochloric acid as follows:              On passing the gas liberated (CO2) through lime water [Ca(OH)2] the white precipitates of CaCO3 is obtained. On passing excess carbon dioxide, the solution of calcium hydrogen carbonate is obtained.