Question
Acidity of diprotic acids in aqueous solutions increases in the order
A.
$${H_2}S < {H_2}Se < {H_2}Te$$
B.
$${H_2}Se < {H_2}S < {H_2}Te$$
C.
$${H_2}Te < {H_2}S < {H_2}Se$$
D.
$${H_2}Se < {H_2}Te < {H_2}S$$
Answer :
$${H_2}S < {H_2}Se < {H_2}Te$$
Solution :
Acidic strength of hydrides increases as the size of central atom increases which weakens the $$M—H$$ bond. Since, the size increases from $$S$$ to $$Te$$ thus acidic strength follows the order.
$${H_2}S < {H_2}Se < {H_2}Te$$
$${\text{Acidic}}\,{\text{nature}} \propto \frac{1}{{{\text{Bond}}\,{\text{dissociation}}\,{\text{enthalpy}}}}$$
$$S$$ to $$Te$$ size increases, bond dissociation enthalpy decreases and acidic nature increases.