The equilibrium constant expression for this reaction can be written as:
Kc = [CH3CH2COOC2H5][H2O]/[CH3CH2COOH][C2H5OH]
Step-by-step explanation:
The reaction between propanoic acid and ethanol in the presence of hydrochloric acid is an esterification reaction, which can be represented by the following equilibrium equation:
Propanoic acid + Ethanol ⇌ Ethyl propanoate + Water
The balanced chemical equation for this reaction is:
CH3CH2COOH + C2H5OH ⇌ CH3CH2COOC2H5 + H2O
where CH3CH2COOH is propanoic acid, C2H5OH is ethanol, CH3CH2COOC2H5 is ethyl propanoate, and H2O is water.
The equilibrium constant expression for this reaction can be written as:
Kc = [CH3CH2COOC2H5][H2O]/[CH3CH2COOH][C2H5OH]
where the square brackets indicate the concentration of each species at equilibrium.
Note that the presence of hydrochloric acid does not affect the equilibrium equation or the equilibrium constant expression, but it does catalyze the reaction by increasing the rate of the forward and backward reactions.