Question

Why we included water in Kc Equilibrium ?

A) Water is always a reactant in chemical reactions.

B) Water concentration remains constant in a closed system.

C) Water is used as a solvent, affecting the reaction's equilibrium position.

D) Water molecules are involved in the reaction as products.

E) Including water is a convention and does not affect the equilibrium constant.

Answer 1

The concentration of water is omitted from the Keq expression in reactions where it acts as a solvent because its concentration remains constant due to its large excess, and its activity is considered to be 1.

Step-by-step explanation:

The inclusion of water in the equilibrium constant (Keq) expression depends on its state and its role in the reaction. When water is the solvent and present in large excess, its concentration does not change significantly during the reaction and is therefore treated as constant.

For liquid or solid solvents like water, their activity is regarded as 1 and is omitted from the equilibrium expression. When involved in gaseous or aqueous equilibrium reactions, only those species whose concentrations change significantly are included in the equilibrium constant expression.