Question

Chemical equilibria have the property that, if disturbed, they readjust to form a new equilibrium (Le Chatelier’s Principle). For example, if component X decreases in concentration, reactions will occur to produce more X until a new equilibrium is achieved. Consider the following equilibrium: CO 2 + H 2 O <-> H 2 CO 3 <-> H + + HCO 3 - If the concentration of CO 2 increases, what do you expect will happen to the concentrations of H 2 CO 3 , H + and HCO 3 - ? A.) All three will increase B.) All three will decrease C.) Carbonic acid will increase, hydrogen ion and bicarbonate ion will decrease D.) Carbonic acid will decrease, hydrogen ion and bicarbonate ion will increase E.) no change

Answer 1

Ans. Le Chatelier’s principle states “if a dynamic equilibrium is disturbed by changing the conditions (Concentration, Volume, Pressure, temperature, etc.), the position of equilibrium shifts to counteract the change to reestablish an equilibrium”.

# Addition of H⁺ (= H₃O⁺, a product) shifts the equilibrium to the left, towards formation of bicarbonate ion (a reactant).

Given: CO₂ + H₂O <-----> H₂CO₃ <----> HCO₃^- + H⁺

# Addition of CO₂ (a reactant) shifts the equilibrium to the RIGHT in an attempt to restore [CO₂] as that of previous equilibrium value. A right shift in the equilibrium leads to formation of more products (H₂CO₃, HCO₃^-, H⁺).

So, correct option is- A. All three will increase.