A manufacturer electroplates a bicycle frame with aluminum to improve corrosion resistance. The plating step uses the following three current settings applied sequentially to the same frame:
• 10.0 A for 30.0 min
• 15.0 A for 45.0 min
• 7.50 A for 1.00 h
Assume 100 % current efficiency for deposition of aluminum according to Al3+ + 3 e− → Al(s).
Additional data:
• Molar mass of Al = 26.98 g mol−1
• Density of Al = 2.70 g cm−3
• Total surface area coated = 1.20 m2
Faraday constant: F=9.6485×104 C mol−1
(a) Compute the total electric charge delivered to the frame during the entire plating sequence.
(b) Determine the total mass of aluminum deposited on the bicycle frame.
(c) Assuming the aluminum forms a uniform layer over the stated surface area, calculate the average thickness of the deposited coating in micrometres (µm). Express your answer to three significant figures.