Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as: CH 3 COOH (l) + C 2 H 5 OH (l) ⇌ CH 3 COOC 2 H 5 (l) + H 2 O (l) (i) Write the concentration ratio (reaction quotient), Q c , for this reaction (note: water is not in excess and is not a solvent in this reaction) (ii) At 293 K, if one starts with 1.00 mol of acetic acid and 0.18 mol of ethanol, there is 0.171 mol of ethyl acetate in the final equilibrium mixture. Calculate the equilibrium constant. (iii) Starting with 0.5 mol of ethanol and 1.0 mol of acetic acid and maintaining it at 293 K, 0.214 mol of ethyl acetate is found after sometime. Has equilibrium been reached?

Question

Philoid · Accepted Answer

(i) The reaction quotient (Q) measures the relative amounts of products and reactants present during a reaction at a particular point in time. It also indicates the direction in which the reaction is going to proceed.

For the given reaction of ethanol and acetic acid that results in the formation of ethyl acetate and water, the reaction quotient is-

CH₃COOH (l)+C₂H₅OH (l)⇌CH₃COOC₂H₅(l)+H₂O (l)

Therefore,

(ii) To find if equilibrium has been reached, we need to calculate the Reaction quotient (Q_c) and compare it with the Equilibrium constant (K_c).

We know that,

Since the value of the Reaction quotient (Q_c) is less than that of the Equilibrium constant (K_c), equilibrium has not been reached yet. The process of reaction is still taking place to form the products.