Questions & Answers

Acetic acid is a weak acid than sulphuric acid because:
a.) It decomposes on increasing temperature
b.) It has less degree of ionization
c.) It has -COOH group
d.) None of the above

Answer Verified Verified
Hint: A weak acid is defined as a substance that partially dissociates when dissolved in a solvent. The strength of a weak acid is quantified in terms of a dissociation constant.

Complete step by step answer:
Acetic acid is systematically named as ethanoic acid. It is a colourless organic compound with the chemical formula \[C{H_3}COOH\]. When undiluted, it is sometimes called glacial acetic acid. On the other hand, sulphuric acid is a mineral acid with the chemical formula \[{H_2}S{O_4}\]. It is a colourless, odourless and viscous liquid that is soluble in water.
Now, a weak acid may be defined as an acid that partially dissociates into its constituent ions in an aqueous solution or water. In contrast, a strong acid fully dissociates into its ions in water. The strength of an acid is judged based on its degree of dissociation (). Higher the degree of dissociation/ionization of an acid, higher is its ionization and the better acid it is.
Sulphuric acid readily ionizes into its constituent ions \[{H^ + }\] and \[S{O_4}^{ - 2}\] as the degree of ionization of sulphuric acid is large. On the other hand, acetic acid doesn’t easily ionize into its constituent ions \[{H^ + }\] and \[C{H_3}CO{O^ - }\] because of its lower degree of ionization. Thus, sulphuric acid is a stronger acid than acetic acid.

Hence, the correct answer is (B).

Note: Remember that the conjugate base of a strong acid is a weak base and the conjugate acid of a strong base is a weak acid. This is according to the Bronsted – Lowry concept.
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