Question

Number of moles of ions produced by the complete dissociation of one mole of Mohr’s salt in water is:

• A. 3
• B. 4
• C. 5
• D. 6

Hint:

To calculate the number of ions, consider the complete dissociation of all components of the salt.

Answer 1

The Correct Option is C

Mohr’s salt, or ammonium iron(II) sulfate, has the chemical formula (NH₄)₂[Fe(SO₄)₂] · 6H₂O.

When it dissolves in water, it breaks down completely:

\( (\text{NH}_4)_2[\text{Fe(SO}_4)_2] \cdot 6\text{H}_2\text{O} \rightarrow 2\text{NH}^+_4 + \text{Fe}^{2+} + 2\text{SO}^{2-}_4 \)

The resulting ions are:

• 2 NH⁺₄ (ammonium ions),
• 1 Fe²⁺ (iron(II) ion),
• 2 SO²⁻₄ (sulfate ions).

Therefore, one mole of Mohr’s salt yields: 2 + 1 + 2 = 5 moles of ions.

Conclusion: The answer is: 5.