Question

Hot concentrated sulphuric acid is a moderately strong oxidizing agent. Which of the following reaction does not show oxidizing behaviour?

• A. ${ Cu + 2H2SO4 -> CuSO4 + SO2 + 2H2O }$
• B. ${3S + 2H2SO4 -> 3SO2 + 2H2O }$
• C. ${ C + 2H2SO4 -> CO2 + 2SO2 + 2H2O }$
• D. ${ CaF2 + H2SO4 -> CaSO4 + 2HF }$

Answer 1

The Correct Option is D

To determine which reaction does not show the oxidizing behavior of hot concentrated sulphuric acid, we must evaluate each given reaction and identify whether a redox process, indicating oxidation and reduction, occurs.

1. Cu + 2H_2SO_4 \rightarrow CuSO_4 + SO_2 + 2H_2O

   In this reaction, copper (Cu) is oxidized as it goes from Cu (0) to Cu⁺² in CuSO₄, and sulfur in H₂SO₄ is reduced as it forms SO₂. This demonstrates the oxidizing behavior of sulphuric acid.

2. 3S + 2H_2SO_4 \rightarrow 3SO_2 + 2H_2O

   Here, sulfur (S) is oxidized from 0 in elemental sulfur to +4 in SO₂. Sulfur from H₂SO₄ acts as the oxidizing agent as it does not change its oxidation state unlike the elemental sulfur, providing evidence of oxidizing behavior.

3. C + 2H_2SO_4 \rightarrow CO_2 + 2SO_2 + 2H_2O

   Carbon (C) is oxidized from 0 in elemental carbon to +4 in CO₂. H₂SO₄ is reduced to SO₂, indicating the oxidizing behavior of sulphuric acid.

4. CaF_2 + H_2SO_4 \rightarrow CaSO_4 + 2HF

   In this reaction, there is no change in the oxidation states of any element involved. This is an acid-base reaction where CaSO₄ and HF are formed. Thus, this reaction does not exhibit the oxidizing behavior of sulphuric acid.

After analyzing each option, it is evident that the reaction CaF_2 + H_2SO_4 \rightarrow CaSO_4 + 2HF does not show the oxidizing behavior of hot concentrated sulphuric acid, hence it is the correct answer.