Changing the pressure
3 marks · EasyFor the following equilibrium:
A chemist measured the percentage of E(g), F(g), and G(g) at equilibrium under different pressure conditions. Use the data to answer the questions.
| Condition | % E(g) | % F(g) | % G(g) |
|---|---|---|---|
| Low pressure | 30 | 30 | 40 |
| High pressure | 25 | 25 | 50 |
State the number of gaseous molecules on each side of the equation.
Describe the effect of increasing the pressure on the position of equilibrium, using the data.
Explain your answer to part (b).
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: 2, Right: 1
(b) The position of equilibrium shifts to the right (towards G(g)) with increased pressure
(c) The data shows more G(g) is present at higher pressure; the right side has fewer gas molecules, so increased pressure favours its formation.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States correct number of gaseous molecules on each side
M1 (b) · 1 mark · Describes the shift in equilibrium with increased pressure using data
M1 (c) · 1 mark · Gives explanation linking number of molecules and pressure effect
Worked solution
(a) Left: 1 (E) + 1 (F) = 2 gaseous molecules; Right: 1 (G) = 1 gaseous molecule.
(b) Increasing pressure causes equilibrium to shift to the right (towards more G(g)), shown by the higher percentage of G(g) at high pressure.
(c) Increased pressure favours the side with fewer gaseous molecules, so more G(g) is formed.