Question

19) Different stages involved in the manufacture of Hydrogen(H₂) gas by Bosch process are given below.

Arrange them in the correct sequence.

• A. c ,e , d ,b , a
• B. c ,d ,b, a, e
• C. b e c d a
• D. b,d ,a ,e ,c

Answer 1

The correct option is C

b e c d a

19) The correct sequence for the preparation of H₂ gas is option C

Industrial methods of preparation of H₂ gas (Bosch Process):

This method involves two stages

b) Preparation of water gas(CO+H₂)

Steam at 170⁰C when passed through white hot coke or charcoal gives a mixture of equal volumes of CO gas and hydrogen known as water gas.

$\mathrm{C}(\mathrm{Hot}\mathrm{coke})+{\mathrm{H}}_2\mathrm{O}(\mathrm{steam})\stackrel{{170}^{\mathrm{o}}\mathrm{C}}{\to }[\mathrm{CO}+{\mathrm{H}}_2](\mathrm{Water}\mathrm{gas})$

e) Removal of carbon monoxide (CO) from water gas:

Water gas obtained is made to pass over Fe₂O₃ (Iron III oxide) (which act as catalyst) and Cr₂O₃ (Chromium III oxide)(promoter) along with super heated steam at 500⁰C. Carbon monoxide gets oxidised to CO₂ leaving behind hydrogen gas.

$[\mathrm{CO}+{\mathrm{H}}_2](\mathrm{Water}\mathrm{gas})+{\mathrm{H}}_2\mathrm{O}(\mathrm{steam})\underset{{500}^{\mathrm{o}}\mathrm{C}}{\overset{{\mathrm{Fe}}_2{\mathrm{O}}_3}{\to }}{\mathrm{CO}}_2(\mathrm{Carbon}\mathrm{dioxide})+2{\mathrm{H}}_2(\mathrm{Hydrogen}\mathrm{gas})$

c) Removal of CO₂

The CO₂ gas is removed by compressing the gas at 30 atm pressure and passing through water.

${\mathrm{CO}}_2(\mathrm{Carbon}\mathrm{dioxide})+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{Steam}\right)\stackrel{300\mathrm{atm}}{\to }{\mathrm{H}}_2{\mathrm{CO}}_3(\mathrm{Carbonic}\mathrm{acid})$

d) Removal of water vapour:

The water vapour present in the gas can be removed by cooling the gas to -20⁰C.

a) Removal of unoxidised CO:

The traces of carbon monoxide remaining unoxidised can be removed by passing the gas through ammonical cuperous chloride solution.

$\mathrm{CuCl}(\mathrm{Cuprous}\mathrm{chloride})+\mathrm{CO}\left(\mathrm{Carbonmonoxide}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{water}\right)\to \mathrm{CuCl}.\mathrm{CO}.2{\mathrm{H}}_2\mathrm{O}(\mathrm{Copper}\mathrm{I}\mathrm{chloride}\mathrm{carbon}\mathrm{monoxide}\mathrm{dihydrate})$