For the reaction in equilibrium N2(g) + 3H2(g) 2NH3(g), H = -Q Reaction is favoured in forward direction by:
- use of catalyst
- decreasing concentration of N2
- low pressure, high temperature and high concentration of ammonia
- high pressure, low temperature and higher concentration of H2
Answer
(4) high pressure, low temperature and higher concentration of H2
Solution
The forward reaction is exothermic ( H = -Q) and goes from 4 mol of gas to 2 mol of gas ( ng = -2).
By Le Chatelier's principle: high pressure shift towards fewer gas moles (forward); low temperature favours the exothermic forward reaction; more H2 (reactant) forward shift.
A catalyst does not shift the equilibrium; removing N2 or adding NH3 shifts it backward.
Answer: (4)