What is the equivalent weight of Mohr's Salt when it is oxidized by KMnO₄ in an acidic medium?
The equivalent weight of Mohr's Salt when it is oxidized by KMnO₄ in an acidic medium is 78.4 g/mol.
Calculation of Equivalent Weight:
The equivalent weight of a substance is calculated based on its molecular weight and the number of electrons involved in the reaction. In the case of Mohr's salt (Fe(NH4)2(SO4)2·6H2O), when it is oxidized by KMnO₄ in an acidic medium, one mole of KMnO₄ reacts with five moles of Fe(NH4)2(SO4)2·6H2O.
The molecular weight of Mohr's salt is 392. Therefore, to calculate the equivalent weight, we divide the molecular weight by the number of moles of KMnO₄ used in the reaction, which is 5 (since the stoichiometric ratio is 1:5). So, the equivalent weight is 392/5 = 78.4 g/mol.
Therefore, the correct answer is option D (78.4 g/mol).