Question

For the given reaction :
$2A\left(g\right)+B\left(g\right)\rightleftharpoons C\left(g\right),△H=-ve$
Which of the following conditions favour the formation of products?

• A. Low Pressure
  
• B. High Pressure
  
• C. Low Temperature
  
• D. High Temperature

Answer 1

Answer: (B), (C)

Low Temperature


Given reaction :
$2A\left(g\right)+B\left(g\right)\rightleftharpoons C\left(g\right),△H=-ve$

Since the forward reaction is exothermic reaction i.e. heat is liberated. So, temperature increases in the forward direction.
Decreasing temperature will favor the formation of products in case of exothermic reaction.
Pressure conditions:

Calculating $\Delta n_g$ for the reaction:
$\Delta n_g=1-3=-2$
$\Delta n_g<0$

The reaction takes place with reduction in number of gaseous moles in the forward side. When a high pressure is applied $\frac{n_g}{V}\uparrow$. The reaction goes where there is a reduction in number of gaseous moles, that is in the forward direction.
So, for the yield of product to be the high i.e. $C\uparrow$ , a high pressure should be applied