The magnitude of the change in oxidising power of the MnO 4 - / Mn 2 + couple is x × 10 - 4 V if the H + concentration is decreased from 1 M to 10 - 4 M at 25 ° C . (Assume concentration of MnO 4 - and Mn 2 + to be same on change in H + concentration). The value of x is __________. (Rounded off to the nearest integer) [Given: 2 . 303 RT F = 0 . 059 ]

Step-by-step solution

Eqn is- MnO 4 - + H ⊕ + 5 e - → Mn + 2 + 4 H 2 O Nernst equation: E cell   = E Cell   0 - 0 . 059 5 log Mn + 2 MnO 4 - 1 H + 8 (I) Given H ⊕ = 1 M E 1 = E 0 - 0 . 059 5 log Mn + 2 MnO 4 - (II) Now: H ⊕ = 10 - 4 M E 2 = E 0 - 0 . 059 5 log Mn + 2 MnO 4 - × 1 10 - 4 8 = E 0 - 0 . 059 5 log Mn + 2 MnO 4 - + 0 . 059 5 log 10 - 32 therefore: E 1 - E 2 = 0 . 059 5 × 32 = 0 . 3776   V = 3776 × 10 - 4 x = 3776