Question

Metal plating is done by passing a current through a metal solution. For example, an item can become gold plated by attaching the item to a power source and submerging it into an Au³⁺ solution. The item itself serves as the cathode, at which the Au³⁺ ions are reduced to Au(s). A piece of solid gold is used as the anode and is also connected to the power source, thus completing the circuit. What mass of gold is produced when 15.1 A of current are passed through a gold solution for 31.0 min?

Answer 1

Answer:

172 g

Explanation:

Let's consider the reduction of Au³⁺ to Au.

Au³⁺(aq) + 3 e⁻ → Au(s)

In order to find the mass of gold produced, we will use the following relations.

• 1 min = 60 s
• 1 A = 1 C/s
• The charge of 1 mole of electrons is 96,468 C (Faraday's constant).
• 1 mole of Au is deposited when 3 moles of electrons circulate.
• The molar mass of Au is 196.97 g/mol.

The mass of gold produced when 15.1 A of current are passed through a gold solution for 31.0 min is:

$31.0min \times \frac{60s}{1min} \times \frac{15.1C}{s} \times \frac{1mole^{-} }{96,468C} \times \frac{3molAu}{1mole^{-} } \times \frac{196.97gAu}{1molAu} = 172 gAu$