Question

Methane and water react to form hydrogen and carbon monoxide, like this:

CH4(g)+H20(g) → 3 H,(g) + CO(g)
The reaction is endothermic. Suppose a mixture of CH4, H20, H2 and CO has come to equilibrium in a closed reaction vessel. Predict what change, if any, the perturbations in the table below will cause in the composition of the mixture in the vessel. Also decide whether the equilibrium shifts to the right or left.
1st row: perturbation | change in composition | shift in equilibrium
2nd row: The temperature is lowered | Thre pressure of CH4, will ____ | to the right/left/none
3rd row: The temperature is raised| Thre pressure of CO, will ____ | to the right/left/none

Answer 1

Based on Le Chatelier's principle, if a system at equilibrium is disturbed by changes in the temperature, pressure or concentration, then the equilibrium will shift in a direction to undo the effect of the induced change.

The given reaction is endothermic i.e, heat is supplied:

CH4(g) + H2O (g) + heat ↔ 3H2(g) + CO(g)

a) When the temperature is lowered, heat is being removed from the system. The reaction will move in a direction to produce more heat i.e. to the left.

Hence, the pressure of CH4 will increase and equilibrium will shift to the left

b) When the temperature is raised, heat is being added to the system. The reaction will move in a direction to consume the added heat i.e. to the right.

Hence, the pressure of CO will increase and equilibrium will shift to the right