Question

Calculate the equivalent mass of K₂Cr₂O₇ in an acidic medium.

Answer 1

In an acidic medium, K₂Cr₂O₇ gets reduced as:

\[\ce{Cr2O^{2-}_7 + 14H+ + 6e- -> 2Cr^{3+} + 7H2O}\]

So, n-factor = 6.

Molecular mass of K₂Cr₂O₇:

2K = 2 × 39 = 78

2Cr = 2 × 52 = 104

7O = 7 × 16 = 112

Total = 78 + 104 + 112 = 294

Equivalent mass = `"Molecular mass"/n`

= `294/6`

= 49

The equivalent mass of K₂Cr₂O₇ in acetic medium is 49 g eq⁻¹.