Question

Lady Gaga wants to create chromium-plated bling to wear for her next concert. How many amps of current are required to plate out 2.0 g of solid chromium in one hour from an aqueous CrCl3 solution at 25°C?

A. 3.09 amps

B. 1.03 amps

C. 3711 amps

D. 186 amps

E. 61.8 amps

The answer is A, please show work

Answer 1

The electroplating reaction is : Cr³⁺ (aq) + 3 e^- Cr (s)

mass Cr plated = 2.0 g

moles Cr plated = (mass Cr plated) / (molar mass Cr)

moles Cr plated = (2.0 g) / (51.996 g/mol)

moles Cr plated = 0.03846 mol

moles of electron = 3 * (moles Cr plated)

moles of electron = 3 * (0.03846 mol)

moles of electron = 0.1154 mol

Charge = (moles of electron) * (Faraday's constant)

Charge = (0.1154 mol) * (96485 C/mol)

Charge = 11133.7 C

time = 1 hr = 3600 s

current required = (charge) / (time)

current required = (11133.7 C) / (3600 s)

current required = 3.09 A