Question

Identify the stronger acid in each of the following pairs:

Part a H2S or H2Se

Part B HI or H2Te

Part C HNO2 or HNO3

Part D H2SO3 or H2SeO3

Answer 1

Part A)

Since Se is larger than S, the H–Se bonds is longer than the H–S bonds. The H–Se bond is therefore weaker than the H–S bond and thus H₂Se is a stronger acid

H₂S < H₂Se

Part B)

Iodine is more electronegative than Te

HI > H₂Te

Part C)

Increase in the number of electronegative atoms increases the acidity

HNO₃ > HNO₂

Part D)

Sulfur is more electronegative than selenium and attracts oxygen's electrons and weakens the O-H bond to a greater extent. This enables the release of H⁺ more easily

H₂SO₃ > H₂SeO₃