Question Details

A solution of copper sulphate is electrolysed for 10 minutes with a current of 1.5 ampere. The mass of copper deposited at the cathode is:


Molar mass of Cu=63 g mol−1, 1F =96487 C mol−1

Options

A

2.4036 g

B

1.7018 g

C

0.5876 g

D

0.2938 g

Show Answer

Correct Answer :

Option D

0.2938 g

0.2938 g

Solution :

**Step 1: Identify the electrochemical reaction**
At the cathode copper(II) ions are reduced to metallic copper:

Cu^{2+}+2e^{-}\rightarrow Cu\;(s)


Thus, 2 moles of electrons are required to deposit 1 mole of Cu (n = 2).

**Step 2: Convert the electrolysis time to seconds**
The current is applied for 10 minutes.

t = 10\ \text{min}\times 60\ \frac{\text{s}}{\text{min}} = 600\ \text{s}

**Step 3: Calculate the total charge passed**
Charge (Q) equals current (I) multiplied by time (t).

Q = I \times t = 1.5\ \text{A}\times 600\ \text{s}= 900\ \text{C}

**Step 4: Determine the amount of copper deposited (in moles)**
Using Faraday’s law:

n_{\text{Cu}} = \frac{Q}{n\,F} = \frac{900\ \text{C}}{2 \times 96487\ \text{C mol^{-1}}}


n_{\text{Cu}} \approx \frac{900}{192974}\ \text{mol}\approx 4.665\times10^{-3}\ \text{mol}

**Step 5: Convert moles of copper to mass**
Molar mass of Cu = 63 g mol⁻¹.

m = n_{\text{Cu}}\times M = 4.665\times10^{-3}\ \text{mol}\times 63\ \frac{\text{g}}{\text{mol}}


m \approx 0.2938\ \text{g}

**Result**
The mass of copper deposited at the cathode after 10 minutes with a 1.5 A current is **0.2938 g**.

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