Question

A manganese electrode was oxidized electrically. If the mass of the electrode decreased by 225 mg during the passage of 1580 coulombs, what was the oxidation state of the manganese produced

Answer 1

Oxidation state of Mn = +4

Step-by-step explanation:

Atomic mass of Mn = 55g/mol

From Faraday's law of electrolysis,

Electrochemical equivalent =
`(mass)/(charge)`

i.e Z =
`(m)/(Q)` =
`(0.225g)/(1580C)` = 0.0001424 g/C

But Equivalent weight, E = atomic mass ÷ valency = Z × 96,485

⇒
`(55)/(valency)` = 0.0001424 × 96,485

∴ Valency of Mn = +4