In this reaction, the functional group involved is the carboxylic acid group -COOH present in ethanoic acid CH3COOH .The reaction mechanism for the reaction between ethanoic acid and sodium hydroxide is an acid-base reaction, also known as a neutralization reaction. Here's the step-by-step mechanism:1. Ethanoic acid CH3COOH donates a proton H+ to the hydroxide ion OH- from sodium hydroxide NaOH .CH3COOH + OH- CH3COO- + H2O2. The acetate ion CH3COO- formed in the previous step combines with the sodium ion Na+ from sodium hydroxide to form sodium ethanoate CH3COONa .CH3COO- + Na+ CH3COONaOverall reaction:CH3COOH + NaOH CH3COONa + H2OIn summary, ethanoic acid reacts with sodium hydroxide through an acid-base reaction mechanism, involving the carboxylic acid functional group, to form sodium ethanoate and water.