Question

The correct order of acidity of the following hydra acids is:

• A. HF> HCL >HBr >HI
• B. HF
• C. HFHBr>HI
• D. HF>HCLHI

Answer 1

The Correct Option is B

The correct order of acidity is HF < HCl < HBr < HI.

Here's why:

• Hydracids: Hydracids are binary acids composed of hydrogen and a halogen (Group 17 element).
• Acidity Trends: The acidity of hydracids increases down the group. This is because:
  • Bond Strength: As you move down the group, the size of the halogen atom increases. This leads to a weaker H-X bond (where X is the halogen). A weaker bond is easier to break, leading to increased H⁺ ion concentration in solution, and a stronger acid.
  • Bond Dissociation Energy: The bond dissociation energy decreases down the group:
    • H-F bond is very strong
    • H-I bond is very weak
  • HF Exception: HF is a weak acid while all other hydrohalic acids are strong acids. While electronegativity differences play a part in the acidity of HF, the stronger bond strength prevents complete dissociation. HF has very strong Hydrogen bonds that makes it less acidic in solution.
• In summary, bond strength is the dominant factor determining acidity in this series. The weaker the H-X bond, the stronger the acid.

Correct Answer: HF < HCl < HBr < HI