Question

For the gaseous reaction
$ C_2H_4 + H_2 \ce{<=> }C_2H_6 $ , $ \Delta\, H = −130 \,kJ\, mol^{−1} $ carried in a closed vessel, the equilibrium concentration of the $ C_2H_6 $ can definitely be increased by :

• A. increasing temperature and decreasing pressure
• B. decreasing temperature and increasing pressure
• C. increasing temperature and pressure both
• D. decreasing temperature and pressure both

Answer 1

Answer: (B)

According to Le-Chatelier principle exothermic reactions are favourable at low

temperature. The reaction in which number of moles decrease are favourable at high pressure or low volume.

$C _{2} H _{4}+ H _{2} \rightleftharpoons C _{2} H _{6} ; \Delta \,H=-130 \,kJ\, mol ^{-1}$

$\because$ the reaction is exothermic and number of moles of reactants are decreasing

$\therefore $ the reaction rate is increased by decreasing temperature and increasing pressure.