Available Answers

1. 1.

   State how hydrogen occurs in the free state. Name three compounds containing hydrogen in the combined state.

2. 2.

   Starting from zinc how would you obtain hydrogen using - (a) Steam (b) A dilute acid (c) An alkali.( Give balanced equations for each & name the product formed in each case other than hydrogen). Name a metal which will not react with the reactants above to get hydrogen.

3. 3.

   'Hydrogen is obtained by electrolysis of acidified water.' Answer the following pertaining to the preparation of hydrogen by electrolysis. (a) The meaning of the term 'electrolysis' & 'electrolyte'. (b) Name the electrode - (i) through which the current enters the electrolyte. (ii) at which hydrogen is liberated.

4. 4.

   In the laboratory preparation of hydrogen from zinc & dilute hydrochloric acid - state a reason for:

   1. Addition of traces of copper [II] sulphate to the reaction medium.
   2. Collecting the hydrogen by downward displacement of water and not air & collecting it after all the air in the apparatus is allowed to escape.
   3. Having the end of the thistle funnel dip below the level of the acid in the flask.
5. 5.

   In the industrial method of preparation of hydrogen by the Bosch process - give

   1. balanced equations for the first two main steps in the production of hydrogen.
   2. the reason for use of addition of a promoter to the catalyst in the final step.
   3. the name of the solution which absorbs the unreacted carbon monoxide.
6. 6.

   State the following pertaining to the physical properties of hydrogen:
   (a) Colour & odour (b) Solubility in water (c) Effect on moist blue litmus paper.