Question

What are the products?
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}} \to$
A.${\text{ }}{{\text{H}}_{\text{2}}}{{\text{O}}^{\text{ + }}}{\text{ + HS}}{{\text{O}}_{\text{4}}}^{\text{ - }}$
B.${\text{ }}{{\text{H}}_3}{{\text{O}}^{\text{ + }}}{\text{ + HS}}{{\text{O}}_{\text{4}}}^{\text{ - }}$
C.${\text{ }}{{\text{H}}^{\text{ + }}}{\text{ + HS}}{{\text{O}}_{\text{4}}}^{\text{ - }}$
D.${\text{ }}{{\text{H}}_3}{{\text{O}}^{\text{ + }}}{\text{ + S}}{{\text{O}}_{\text{4}}}^{\text{ - }}$

Answer 1

${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}$ is sulphuric acid and it reacts with water to form a cation and an anion. The cation is the only positive ion that is formed in the medium and is called the hydronium ion.

Complete step by step solution:
Every acid is considered as a proton donor as per the Lowry and Bronsted definition of acids. As soon as it is put into water, it furnishes hydrogen ions which, being a proton, are in search of lone pairs of electrons to gain stability. This stability to it is provided by the lone pair of electrons on the oxygen atom in the water molecule. Hence, the hydronium ion is formed as per the following reaction:
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}{\text{ }} \to {{\text{H}}^ + }{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}} \to {{\text{H}}_{\text{3}}}{{\text{O}}^ + }$
After losing one proton, the sulphuric acid get converted to the bisulphate anion,
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}{\text{ }} \to {{\text{H}}^ + }{\text{ + HS}}{{\text{O}}_{\text{4}}}^{\text{ - }}$.
Hence, the ions formed in the reaction medium after the dissociation of sulphuric acid are the hydronium ion and the bisulphate ion.

Hence, the correct answer is option B.

Notes: After the bisulphate ion is formed, there is yet another proton left, hence the sulphuric acid is called a dibasic acid, as it has two replaceable hydrogen ions. The basicity of an acid is defined as the number of replaceable hydrogen ions present in the acid molecule. The examples of other dibasic acids include sulphurous acid, oxalic acid, tartaric acid, etc. Nitric acid and hydrochloric acids are examples of monobasic acids. An example of a tribasic acid is the phosphoric acid.