One kind of battery used in watches contains mercury(II) oxide. As current flows, the mercury(II) oxide is reduced to mercury.
HgO(s) + H2O( ) + 2 e– Hg( ) + 2 OH–(aq)
If 2.3 10–5 amperes flows continuously for 1200 days, what mass of Hg( ) is produced?
The battery in my calculator is on the blink so I've estimated the following. Be sure to run these calculations yourself.
Coulombs = amperes x seconds
C = 2.3E-5 A x 1200 days x 24 hr/day x 60 min/hr x 60 sec/min = about 2,000 Coulombs.
You know that 96,485 C will deposit 1 equivalent weight of Hg which is 200.6/2 = 100.3 grams. So how much Hg will be deposited with 2000 C?
That's 100.3 g x (2,000 C/96,485 C) = ? grams Hg(s)
Post your work if you get stuck.