Question

Arrange the following: ${\mathrm{H}}_2\mathrm{S},{\mathrm{H}}_2\mathrm{O},{\mathrm{H}}_2\mathrm{Se}\&{\mathrm{H}}_2\mathrm{Te}$ in order of increasing acidity

Answer 1

The acidity of hydrides:

• The acidity of given hydrides of the oxygen family will be ${\mathrm{H}}_2\mathrm{O}<{\mathrm{H}}_2\mathrm{S}<{\mathrm{H}}_2\mathrm{Se}<{\mathrm{H}}_2\mathrm{Te}$.

Reason:

• The acidity of hydrides depends on the bond dissociation enthalpy.
• The Bond Dissociation Enthalpy is the measurement of the amount of energy needed during an endothermic reaction to break down a chemical bond and separate it into two distinct atoms, each of which retains one of the first mutual pair's electrons.
• The acidity of given hydrides of the oxygen family increases down the group with a decrease in the bond dissociation enthalpy.
• Thus, the correct order of acidity will be ${\mathrm{H}}_2\mathrm{O}<{\mathrm{H}}_2\mathrm{S}<{\mathrm{H}}_2\mathrm{Se}<{\mathrm{H}}_2\mathrm{Te}$.