Question

To precipitate 1 gram silver on a surface using saturated AgNO3 solution at 2 amp current, how many hours does it take?

Answer 1

1) Determine moles of Ag plated out:

1 g divided by 26.98 g/mole = 0.037064 mol

2) Determine moles of electrons required:

Ag⁺ + 1e¯ ---> Ag

therefore, every mole of Ag plated out requires one mol of electrons.

0.037064 mol x 2 = 0.074128 mol e¯ required

3) Convert moles of electrons to Coulombs of charge:

0.074128 mol e¯ x 96,485.309 C/mol (Faraday constant) = 7152.3579 C

4) Convert to seconds required to deliver the Coulombs determined in step 3 (remember that 1 A = 1 C/sec):

7152.3579 C divided by 2 C/sec = 3576.1789 sec

5) Convert to hours:

3576.1789 sec divided by 3600 sec/hour = 0.9933 hours (Can round up to 1 hour)