Question

Which of the following are strong acids: \[{H_2}S{O_4}\], \[HI\], \[HF\], \[{H_3}P{O_3}\], and\[HN{O_3}\]?

Answer 1

Hint: Arrhenius is one of the concepts for acid and bases. The world’s first chemist to talk about acid and bases is Swedish chemist Arrhenius. Depending on his concept and limitation later so many concepts are developed. Arrhenius is the birthplace of the concept of acids and bases. Followed by Arrhenius chemist the concept of acids and bases discusses Bronsted and Lowry in the world.

Complete answer:
The chemical form of sulphuric acid is \[{H_2}S{O_4}\].
The chemical form of nitric acid is \[HN{O_3}\].
The chemical form of phosphoric acid is \[{H_3}P{O_3}\].
The chemical form of hydrogen fluoride is \[HF\].
The chemical form of hydrogen iodide is \[HI\].
The \[pKa\] of sulphuric acid is \[ - 3\].
The \[pKa\] of nitric acid is \[ - 1.4\].
The \[pKa\] of phosphoric acid is \[1.3\].
The \[pKa\] of hydrogen fluoride is \[3.7\].
The \[pKa\] of hydrogen iodide is \[ - 10\].
The decreasing order of acidity of the given acids is below,
\[HI > {H_2}S{O_4} > HN{O_3} > {H_3}P{O_3} > HF\]

Note:
In general, the pH value of all acids is in between \[{\text{0}}{\text{.9}}\]-\[6.9\] and all the bases are in between \[7.1 - 14.0\]. Arrhenius’s theory has some limitations and one of the main limitations is that it does not explain the behavior of acids and bases in non-aqueous solvents such as acetone etc, it is not able to explain the acid which doesn’t contain hydrogen and bases don’t contain hydroxyl ions in the formula. Ammonia is a well-known base that is not acceptable as the base in Arrhenius base. These limitations are overcome by further coming theories like Bronsted and Lowry’s concept of acids and bases.