Question

Question 9.36 What do you understand by the terms:

(i) hydrogen economy (ii) hydrogenation (iii) ‘syngas’ (iv) water-gas shift reaction (v) fuel-cell ?

Class XI Hydrogen Page 290

Answer 1

(i) Hydrogen economy :-Hydrogen has promising potential for use as a non polluting fuel of future.so, we can say that in future Hydrogen will be our economy system. The basic principle of hydrogen economy is the transportation and storage of energy in the form of liquid or gaseous dihydrogen.

(ii) Hydrogenation:- Addition of dihydrogen(H2) to the organic compounds , containing double or triple bonds in the presence of a catalyst is known as hydrogenation. Hydrogenation of vegetable oils using nickel as catalyst gives edible fats (margarine and vanaspati ghee}.
reaction is -
vegetable oil + H2--(Ni,473K)-->vegetable ghee)


(iii) syn gas :- this is the mixture of CO and H2 . This is also known as synthesis gas.reaction of steam on hydrocarbons or coke at high temperature in the presence of catalyst yields syn gas e.g.,
CH4 + H2O --(1270K,Ni)-->{CO + H2}- syn gas.
Syn gas also produced by the process of coal gasification.
C(s) + H2O(g) ---> {CO + H2}- syn gas


(iv) water gas shift reaction :- the amount of dihydrogen in water gas can be increased by mixing it with steam and then passing the mixture over heated 500°C catalyst.
CO + H2 + H2O ---(catalyst,∆)--> {CO + 2H2}
This reaction is known as water gas shifting reaction.

(v) Fuel cell :- fuel cell is the device which converts the energy produced during the combustion of a fuel directly into electrical energy. Ex:-hydrogen-oxygen fuel cell. It does not cause any pollution. Fuel cells generated electricity with conversion efficiency of 70-85% .