Question

How much electricity in terms of Faraday is required to produce.

1. 20.0 g of Ca from molten CaCl₂ ? 

2. 40.0 g of Al from molten Al₂O₃ ?

Answer 1

1. The electrode reaction is 

Ca²⁺ + 2e^- → Ca

Electricity required to produce 40 g of Ca = 2 F

Electricity required to produce 20 g of Ca = 1 F

2. The electrode reaction is Al³⁺+ 3e^- → Al 

Electricity required to produce 27 g of Al = 3 F

Electricity required to produce 40 g of Al = \(\frac{3F\times40}{27}\)

= 4.44 F