<P> Acetic acid has 349 kcal per 100 g . Vinegar is typically 4--18% acetic acid by mass . Vinegar is used directly as a condiment, and in the pickling of vegetables and other foods . Table vinegar tends to be more diluted (4% to 8% acetic acid), while commercial food pickling employs solutions that are more concentrated . The proportion of acetic acid used worldwide as vinegar is not as large as commercial uses, but is by far the oldest and best - known application . </P> <P> Acetic acid undergoes the typical chemical reactions of a carboxylic acid . Upon treatment with a standard base, it converts to metal acetate and water . With strong bases (e.g., organolithium reagents), it can be doubly deprotonated to give LiCH CO Li . Reduction of acetic acid gives ethanol . The OH group is the main site of reaction, as illustrated by the conversion of acetic acid to acetyl chloride . Other substitution derivatives include acetic anhydride; this anhydride is produced by loss of water from two molecules of acetic acid . Esters of acetic acid can likewise be formed via Fischer esterification, and amides can be formed . When heated above 440 ° C (824 ° F), acetic acid decomposes to produce carbon dioxide and methane, or to produce ketene and water: </P> <Dl> <Dd> CH COOH → CH + CO </Dd> <Dd> CH COOH → CH CO + H O </Dd> </Dl> <Dd> CH COOH → CH + CO </Dd>

Why is ethanoic acid liquid at room temperature