TABLE 28.1 Typical cathode efficiencies in electroplating and values of plating constant C. Plate Metal" Cadmium (2) Chromium (3) Copper (1) Gold (1) Nickel (2) Silver (1) Tin (4) Zinc (2) Electrolyte Cyanide Chromium-acid-sulfate Cyanide Cyanide Acid sulfate Cyanide Acid sulfate Chloride Cathode Efficiency (%) 90 15 98 80 95 100 90 95 Plating Constant Ca mm/amp-s -2 6.73 x 10-2 2.50 x 10- 7.35 x 10-2 10.6 x 10-2 3.42 x 10- 10.7 x 10-2 4.21 x 10- 4.75 x 10- in /amp-min -4 2.47 x 10- 0.92 x 101 2.69 x 101 3.87 x 107 1.25 x 107 3.90 x 107 1.54 x 107 1.74 x 107 4 4 Compiled from [17]. "Most common valence given in parenthesis (); this is the value assumed in determining the plating constant C. For a different valence, compute the new Cby multiplying C value in the table by the most common valence and then dividing by the new valence.