Changing the pressure
3 marks · EasyNitrogen dioxide and dinitrogen tetroxide are involved in the following equilibrium:
State the total number of gaseous molecules on each side of the equation.
If the pressure of the system is increased, predict which direction the equilibrium will shift.
Explain your answer to part (b) in terms of gas molecules.
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) Right / Towards N2O4(g)
(c) The equilibrium shifts to the side with fewer gas molecules to reduce the effect of increased pressure.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States 2 molecules on the left and 1 on the right
B1 (b) · 1 mark · Identifies that the equilibrium shifts right (towards fewer molecules)
B1 (c) · 1 mark · Gives a reason related to number of gas molecules and pressure
Worked solution
(a) Left: 2 molecules (2NO_2(g)), Right: 1 molecule (N_2O_4(g)).
(b) The equilibrium will shift to the right.
(c) Because there is one molecule of gas on the right and two on the left, increasing pressure favours the side with fewer gas molecules to reduce the pressure.