Changing the pressure
2 marks · EasyThe following reaction is at equilibrium at 400 K:
If the total pressure is doubled, predict the effect on the amount of A(g) formed at equilibrium. Show your reasoning.
Calculate the number of gaseous molecules on each side of the equation.
State whether the amount of A(g) at equilibrium will increase, decrease, or stay the same. Explain your answer.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Left: 1, Right: 2
(b) The amount of A(g) will decrease, because increasing pressure favours the side with fewer gas molecules (A2(g)).
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States 1 gaseous molecule on the left, 2 on the right
M1 (b) · 1 mark · Correct prediction and explanation based on pressure and number of molecules
Worked solution
(a) Left: 1 gas molecule (A_2(g)); Right: 2 gas molecules (2A(g)).
(b) Increasing pressure will decrease the amount of A(g) at equilibrium, because the change favours the side with fewer gas molecules (A_2(g)).