Question

Chromium metal can be plated out from an acidic solution containing $Cr{O}_3$ according to the following equation $Cr{O}_3\left(aq\right)+6H^{+}\left(aq\right)+6e^{-}\to Cr\left(s\right)+3H_{2}O$
Calculate how many grams of chromium will be placed out by $24000$ coulombs (Atomic Weight of Cr$=52$).

• A. $2.15$ gram
• B. $0.36$ gram
• C. $21.5$ gram
• D. None

Answer 1

The correct option is A $2.15$ gram

$Cr{O}_3\left(aq\right)+6H^{+}\left(aq\right)+6e^{-}\to Cr\left(s\right)+3H_{2}O$

$n=6$

Atomic weight of $Cr=52$

$itimest=24000C$

$m=\frac{AtomicWeight}{n\times f}\times i\times t$

$=\frac{52}{6\times 96500}\times 24000=2.155g$

$\therefore 2.15g$ of chromium will be placed out by $24000C$