A jewelry company electroplates rectangular sterling-silver pendants (treated as flat…
CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
A jewelry company electroplates rectangular sterling-silver pendants (treated as flat plates) with a layer of 24-karat gold. Each pendant measures 3.50cm×2.00cm on each face and is 1.00mm thick. Both large faces and all four narrow side faces must be coated, but the two very small end faces can be neglected.
The production target is a uniform gold layer 0.60μm thick on every coated surface. A batch of 25 pendants is mounted on a common cathodic rack and immersed in the gold electrolyte, which contains Au3+ ions.
(a) Calculate the total surface area that will receive the gold coating for the entire batch.
(b) Using the target thickness, determine the total mass of gold that must be deposited (density of gold = 19.3gcm−3).
(c) If the plating line operates at a constant current of 12.0A, determine the minimum time, in minutes, required to achieve the desired coating. (Atomic mass of Au = 197.0gmol−1.)