Question

2 moles of acidified KMnO4 could completely oxidize 3 moles of a substance ‘A’. What is the equivalent weight of ‘A’ in terms of its molecular weight ‘M’?

Answer 1

Given:

• Moles of KMnO₄ used = 2
• Moles of substance A oxidized = 3
• Molar mass of substance A = M g/mol

To find:

The equivalent mass of substance A in terms of molecular mass (M).

Solution:

• The n-factor for KMnO₄ is 5 and let the n-factor for substance A be x
• So, x moles of KMnO₄ will oxidize 5 moles of substance A.
• Therefore, 2 moles of KMnO₄ will oxidize 10/x moles of substance A. Hence, 10/x = 3 ⇒ x= 10/3
• The equivalent weight os a substance is the raio of its molecular weight and the n-factor. Hence, equivalent weight of A = M/x = 3M/10

Answer:

The equivalent mass of substance A in terms of molecular mass (M) = 3M/10.