Question

Oxygen is more electronegative than sulphur yet $H_{2}S$ is more acidic than $H_{2}O$. Because

• A. $H_{2}S$ is a gas at ordinary temperature whereas $H_{2}O$ is a liquid
• B. $H-S$ is weaker than $O-H$ bond
• C. Stronger inter molecular $H$-bonding among $H_{2}O$
• D. $H_{2}O$ has higher boiling point than $H_{2}S$

Answer 1

The correct option is B $H-S$ is weaker than $O-H$ bond

The $S-H$ bond is weaker than the $O-H$ bond, due to the larger size of sulphur atom compared to oxygen. So, $H_{2}S$ more easily donates a proton and is therefore more acidic.