Changing the temperature
2 marks · EasyThe reaction below is at equilibrium: for the forward reaction. Explain, using the value of , the effect on the amount of present at equilibrium if the temperature is increased.
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
Increasing temperature favours the endothermic direction (reverse) since ΔH is negative for the forward direction (exothermic). This will increase the amount of U(g) and decrease the amount of U2 at equilibrium.
Also accept: Amount of U2 decreases as temperature increases; Equilibrium shifts to the right (endothermic direction)
Common mistakes: States that U2 increases; Confuses exothermic/endothermic
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Recognises ΔH is negative, so forward is exothermic.
A1 · 1 mark · States the equilibrium shifts to increase U atoms, so less U2 at equilibrium.
Worked solution
Since ΔH is negative, the forward reaction is exothermic. Increasing temperature favours the endothermic (reverse) direction, so the reaction shifts to produce more U(g) and less U2 at equilibrium.