Topic: Preparation of inorganic compounds: Mohr's salt, potash alum· Principles Related to Practical Chemistry

During the preparation of Mohr's salt solution (Ferrous ammonium sulphate), which of the following acid is added to prevent hydrolysis of Fe^2+ ion?

1. dilute sulphuric acid

2. dilute hydrochloric acid

3. concentrated sulphuric acid

4. dilute nitric acid

Doubtly Asked 30 Oct 2026 NEET UG 2024 neet Save WhatsApp Report

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Answer: 1. dilute sulphuric acid

Key idea: \(\mathrm{Fe^{2+}}\) salts hydrolyse in water, so a little acid is added, and it must not oxidise \(\mathrm{Fe^{2+}}\) nor add other ions.

Dilute \(\mathrm{H_2SO_4}\) suits because sulphate is already in the salt. \(\mathrm{HNO_3}\) is an oxidant and HCl brings chloride, so they are unsuitable. Option 1.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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During the preparation of Mohr's salt solution (Ferrous ammonium sulphate), which of the following acid is added to prevent hydrolysis of Fe^2+ ion?

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