Question

Calculate the mass of chromium formed at the cathode during the electrolysis of molten chromium (III) chloride when 4.0 amperes passes through a circuit for 3 hours, 45 minutes and 20 seconds.

Answer 1

Cr³⁺ + 3e^- $\to$ Cr

Mass of Cr formed = $\frac{Mct}{ZF}$

M molecular weight = 51.99 g

c = 4.0 amp

t = 3h45min20sec = 13,520 sec

Z = 3

F = 96,500 C

Mass of Cr formed = $\frac{51.99×4.0×13,520}{3×96,500}$

Mass of Cr formed = 9.71 g