Question

Calculate the number of grams of copper produced in 5.67 hours by the electrolysis of molten CuCl₂ if the electrical current is 11.7 A.

You may assume the molar mass of elemental copper is 63.546 g/mol.

Answer 1

Electrolysis equation is:

Cu2+ + 2e- ------> Cu

1 mol of Cu requires 2 mol of electron

1 mol of electron = 96485 C

So,1 mol of Cu requires 192970 C

let us calculate the charge passed:

t = 5.67 hr = 5.67*3600 s = 2.041*10^4 s

time, t = 2.041*10^4 s

Q = I*t

= 11.7 A * 2.041*10^4 s

= 2.388*10^5 C

mol of Cu plated = 2.388*10^5/192970 = 1.238 mol

Molar mass of Cu = 63.546 g/mol

mass of Cu = number of mol * molar mass

= 1.238 * 63.546

= 78.6 g

Answer: 78.6 g