Question

Equal volume of 1 M HCI and 1 M H2SO4 neutralized by dil. NaOH and heat released is x and y kcal respectively, then which is correct?

• A. x = y
• B. x = 0.5y
• C. x = 0.4y
• D. x = 2y

Answer 1

The Correct Option is B

To solve this question, we need to understand the concept of heat release during the neutralization reaction. When an acid and a base react, they undergo a neutralization reaction to form water and salt, releasing energy in the form of heat.

In this scenario, we are comparing the heat released when equal volumes of 1 M hydrochloric acid (HCl) and 1 M sulfuric acid (H₂SO₄) are neutralized by dilute NaOH.

1. The neutralization reaction for HCl with NaOH can be represented as:
   \text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2\text{O} \end{split}
   Here, one mole of HCl releases heat 'x' kcal since it's a simple 1:1 neutralization.
2. The neutralization reaction for H₂SO₄ with NaOH occurs in two steps:
   \text{H}_2\text{SO}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O} \end{split}
   For complete neutralization, 1 mole of H₂SO₄ requires 2 moles of NaOH, involving the release of heat in two steps. The total heat released is 'y' kcal.
3. Since one mole of H₂SO₄ results in the release of energy for two moles of NaOH compared to one mole of NaOH in the reaction with HCl, the heat released per mole of NaOH in the neutralization of H₂SO₄ is approximately twice as much as that for HCl.
4. Therefore, x = 0.5y because the heat released 'y' in the reaction involving H₂SO₄ is approximately double the heat 'x' released per mole of NaOH in the reaction involving HCl.

Conclusively, the correct answer is x = 0.5y because the heat released from the full neutralization of 1 M H₂SO₄ is about twice that of 1 M HCl, when considering the stoichiometry of the reactions involved.