1) Gold is frequently purified by electroplating. Typically the gold is dissolve
ID: 864635 • Letter: 1
Question
1) Gold is frequently purified by electroplating. Typically the gold is dissolved in a cyanide solution (which is fairly selective for gold) and then it is pulled out of solution by electroplating. If the electroplating apparatus used a current of 3.5 amperes, then how long will it take (h) to purify one ounce of gold from a gold(III) cyanide solution? (Show your work for full credit)
2) You conduct an experiment where you use a single battery with a charge capacity of 900 mAh to precipitate an unknown metal from a salt solution that was leaking from an old battery. You use a vast excess of the salt, so the amount of metal condensed is limited by the battery. You obtain 3.368 g of the metal. You can assume that the metal was the only substance being reduced in the electrochemical cell and 100% of the listed battery charge is useable. If you were able to determine that the metal ion was a +2 ion, then which metal is it? This metal was used in batteries for a long time (even in
Explanation / Answer
1) i = 3.5 A
W= 1 ounce= 28.349g
Equivalent weight of gold = 196.97/3= 65.66
t= ?
From Faraday's law
W= E x i x t / 96500
t= W x 96500/ E x i
= (28.349 x96500) / (65.66 x3.5)
= 11904.08sec
= 3.30 hour
2) i = 900 mA= 0.9 A
t = 1 hour = 3600sec
W= 3.368g
W= E x i x t /96500
3.368 = E x 0.9 x 3600 / 96500
E= 100.3
molar mass = equivalent mass/2
= 100.3/2
= 50.15 g/mol
the mass nearly eqaul to element Vanadium 50.19
so the unknown metal = V
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