Question

A spoon was silver-plated electrolytically in a AgNO3 solution. If 0.750 g of Ag was deposited on the spoon at a constant current of 20.0 mA, how long (in hours) did the electrolysis take? (1 mA = 1x10–3 A)

11.9 hr

9.32 hr

5.92 hr

8.76 hr

10.1 hr

Answer 1

Answer

9.32 hr

Explanation

Ag⁺(aq) + e -------> Ag(s)

1mole of electrons is required to deposite 1mole of Ag⁺

Number of moles of Ag⁺ = 0.750g /107.87g/mol = 0.006953mol

number of moles of electrons required = 0.006953mol

Number of Columbs required = 0.006953mol × 96485C/mol = 670.86C

20.0mA = 0.0200A

1Ambs = 1Coloumb per second

0.0200A = 0.0200Couloumbs per second

Therefore

Time required for electrolysis = 670.86C/0.0200C/s = 33543s = 9.32 hr