Question

Calculate the current strength (I) and number of moles of electrons required to produce 2.369 × 10⁻³ kg of Cu from CuS0₄ in one hour. (Given: Molar mass of Cu = 63 .5 gm/mol).

Answer 1

Given: Weight, W = 2.369 × 10⁻³ kg

Time, t = 1 hour = 60 × 60 = 3600 s

Molar mass = 63.5 gm/ mol, I = ?, No. of e⁻ = ?

\[\ce{Cu^{2+}_{(aq)}+ 2e-_{(2 moles)}-> Cu_{(s)}}\]

2 moles = 2F = 2 × 96500 C

For 63.5 × 10⁻³ kg = 2 × 96500 C

∴ For 2.369 × 10⁻³ kg = x

∴ `(2 xx 96500 xx 2.369 xx 10^-3)/(63.5 xx 10^-3)`

x = Q = 7200 C

Now, Q = I × t

∴ I = `Q/t = 7200/3600 = 2A`

For 96500 C = 1 mole of e⁻

∴ For 7200 C = y mole of e⁻

∴ y = `7200/96500`

= 0 .07461 mole of e⁻

∴ Current strength (I) = 2 A and the number of moles of electrons required is 0 .07461.