Question

When the first element of the periodic table is treated with dioxygen, it gives a compound whose solid-state floats on its liquid state. This compound has an ability to act as an acid as well as a base. What products will be formed when this compound undergoes authorisation?

Answer 1

The first element is hydrogen and its molecular form is dihydrogen \[\ce{(H2)}\]. It reacts with oxygen to form water whose solid state is ice which is lighter than water and floats over water.

Water is amphoteric in nature, i.e., it acts as an acid in the presence of strong bases and acts as a base in the presence of strong acids.

As an acid

\[\ce{\underset{Acid1}{H2O (l)} + \underset{Base2}{NH3 (aq)} -> \underset{Acids2}{NH^{+}4 (aq)} + \underset{Base1}{OH-(aq)}}\]

\[\ce{\underset{Base1}{H2O (l)} + \underset{Acids2}{H2S (aq)} -> \underset{Acids1}{H2O+ (aq)} + \underset{Base2}{HS-(aq)}}\]

Due to amphoteric character, water undergoes self ionization as shown below:

\[\ce{\underset{Acid1}{H2O (l)} + \underset{Base2}{H2O (base)} -> \underset{(Conjugate acid)}{\underset{Acids2}{H3O+ (aq)}} + \underset{(Conjugate base)}{\underset{Base2}{OH- (aq)}}}\]

This self ionization of water is called auto-protolysis.