Identify the most and the least acidic compound in each of the following sets. Leave the remaining answer in each set blank. a) oxalic acid: most acetic acid: formic acid: least b) 2,4-dinitrobenzoic acid: most p-nitrobenzoic acid: p-bromobenzoic acid: least c) cyclohexanol: phenol: benzoic acid:

(a) The most acidic compound - oxalic acid

    The least  acidic compound - acetic acid

(b) The most acidic compound - 2,4-dinitrobenzoic acid

   The least acidic compound -  p-bromobenzoic acid

(c) The most acidic compound - benzoic acid

    The least acidic compound - cyclohexanol

Explanation:

(a) Presence of electron donating group decreases the acidity of carboxylic acid. Therefore , acetic acid is least acidic due to methyl group on carbon of          -COOH group.

Oxalic acid is the most acidic compound due to presence of 2 -COOH group.

(b) Presence of electron withdrawing group increases the acidity of benzoic acid. 2,4-dinitrobenzoic acid will be more acidic as it has two strong electronegative substituents ( group).

p-bromobenzoic acid will be less acidic than p-nitrobenzoic acid beacuse Br is weaker electron withdrawing group than

(c) pKa value of benzoic acid(4.45) is more than other compounds and cyclohexanol has least pKa value (16).(Since , higher the pKa value , least acidic the compound is )

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante