Question

A mixture of gases is at equilibrium: CH4 (g) + H2O (g) → CO (g) + 3 H2 (g) ∆H = 206.103 kJ (a) Does the equilibrium shift to the left or to the right when some H2O (g) is removed from the reaction mixture? (b) Does the equilibrium shift to the left or to the right when some CO (g) is removed from the reaction mixture? (c) In which direction does the equilibrium shift as the temperature is raised? (d) In which direction does the equilibrium shift as pressure is applied to the system?

Answer 1

A~ When some water gas is removed from the reaction, the equilibrium shifts to the left according to Le Chatelier's principle which states that " if a system at equilibrim is subjected to a change, the system will react in such a way as to oppose or reduce the effect of that change, if it is possible."

B~When some CO gas is removed, then the equilibrium shifts to the right.

C~ Here ∆H=(+) ve i.e. it is endothermic reaction. Enthalpy of product is higher than reactant. The reaction will shift towards forward direction with increasing temperature since the applied heat will be adsorbed in endothermic direction.

D~ With increasing pressure, the reacting system will try to lower the pressure..hence, it will move to the direction where the number of moles is reduced. Here, reactant has 2 mole and product has 4 moles. Hence, with increasing pressure equilibrium shifts to the backward direction.