Question

How many minutes will it take to plate out 4.50 g of Cu from a solution of Cu(NO3)2 (aq) onto the cathode of an electrolytic cell when 8.00 A of current are used?

28.5 min

3.06 × 10^−9 min

14.2 min

1.82 × 10^3 min

Answer 1

Cu+2 +2e----> Cu

two moles of electrons are produced per mole of copper deposited

moles of copper = 4.5/63.5 (atomic weight of copper = 63.5)

moles of metal deposited = 0.071

mole of electrons deposited = 0.071*2= 0.142

quantitiy of electricity required = moles of electrons deposited* 96500 = 0.142*96500=13703coulums

from Quantity of electricty required= current* time(seconds)

=13703= 8*t t= 13703/8= 1713 seconds = 1713/60 minutes=28.5 min ( A is the correct answer)