The passage of 0.95 A current for 40 minutes deposited 0.7493 g Cu fro

1.	The passage of 0.95 A current for 40 minutes deposited 0.7493 g Cu from CuSO4 solution. Calculate the molar mass of Cu.
Answer» Given : Electric current = I = 0.95 A Time = f = 40 min = 40 × 60 = 2400 s Mass of Cu deposited = 0.7493 g Molar mass of Cu = ? Reduction half reaction, \(Cu^{2+}_{(aq)}\) + 2e^- ⟶Cu_(s) Quantity of electricity = Q = I × t = 0.95 × 2400 = 2280 C Number of moles of electrons = \(\frac{2280}{96500}\) = 0.02362 mol ∵ 2 mol electrons deposit 1 mol Cu ∴ 0.02362 mol electrons will deposit, \(\frac{0.02362}{2}\) = 0.01181 mol Cu Now, 0.01181 mol Cu weighs 0.7493 g ∴ 1 mol of Cu weigh, \(\frac{0.7493\times 1}{0.01181}\) = 63.44 g Hence molar mass of Cu 63.44 g mol^-1 ∴ Molar mass of Cu = 63.44 g mol^-1.

The passage of 0.95 A current for 40 minutes deposited 0.7493 g Cu from CuSO4 solution. Calculate the molar mass of Cu.

Answer»

Given :

Electric current = I = 0.95 A

Time = f = 40 min = 40 × 60 = 2400 s

Mass of Cu deposited = 0.7493 g

Molar mass of Cu = ?

Reduction half reaction,

\(Cu^{2+}_{(aq)}\) + 2e^- ⟶Cu_(s)

Quantity of electricity = Q = I × t

= 0.95 × 2400

= 2280 C

Number of moles of electrons = \(\frac{2280}{96500}\)

= 0.02362 mol

∵ 2 mol electrons deposit 1 mol Cu

∴ 0.02362 mol electrons will deposit,

\(\frac{0.02362}{2}\) = 0.01181 mol Cu

Now,

0.01181 mol Cu weighs 0.7493 g

∴ 1 mol of Cu weigh,

\(\frac{0.7493\times 1}{0.01181}\) = 63.44 g

Hence molar mass of Cu 63.44 g mol^-1

∴ Molar mass of Cu = 63.44 g mol^-1.

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