A current of 9.65 A is drawn from a Daniel cell for exactly 1 hr. The loss in mass at anode and gain in mass at cathode, respectively are
Answer & explanation
Correct answer: option 2
The correct answer is option 2. 11.77 g, 11.43 g.
To find the loss in mass at the anode and the gain in mass at the cathode of a Daniel cell, we'll use Faraday's laws of electrolysis.
Daniel Cell Reaction
In a Daniel cell, the reactions at the electrodes are:
Anode Reaction: Zn(s) → Zn²⁺(aq) + 2e⁻
Cathode Reaction: Cu²⁺(aq) + 2e⁻ → Cu(s)
The cell reaction is:
\(\text{Zn(s)} + \text{Cu}^{2+}(aq) \rightarrow \text{Zn}^{2+}(aq) + \text{Cu(s)}\)
Given Data
Current (\(I\)) = 9.65 A
Time (\(t\)) = 1 hour = 3600 seconds
Faraday's constant (\(F\)) = 96500 C/mol (approximately)
Total Charge (Q):
\( Q = I \times t \)
\( Q = 9.65 \text{ A} \times 3600 \text{ s} \)
\(Q = 34,740 \text{ C}\)
The number of moles of electrons transferred is given by:
\(\text{Moles of electrons} = \frac{Q}{F} \)
\(\text{Moles of electrons} = \frac{34,740 \text{ C}}{96,500 \text{ C/mol}} \)
\(\text{Moles of electrons} \approx 0.36 \text{ mol}\)
The molar mass of zinc is 65.38 g/mol.
The loss in mass at the anode can be calculated using:
\(\text{Mass loss} = \text{Moles of electrons} \times \text{Molar mass of Zn}\)
Since 1 mole of Zn releases 2 moles of electrons:
\(\text{Moles of Zn} = \frac{0.36 \text{ mol}}{2} \)
\(\text{Moles of Zn} = 0.18 \text{ mol}\)
\(\text{Mass loss} = 0.18 \text{ mol} \times 65.38 \text{ g/mol}\)
\(\text{Mass loss} \approx 11.77 \text{ g}\)
The molar mass of copper is 63.55 g/mol. The gain in mass at the cathode can be calculated similarly:
\(\text{Mass gain} = \text{Moles of electrons} \times \text{Molar mass of Cu}\)
Since 1 mole of Cu²⁺ accepts 2 moles of electrons:
\(\text{Moles of Cu} = \frac{0.36 \text{ mol}}{2}\)
\(\text{Moles of Cu} = 0.18 \text{ mol}\)
\(\text{Mass gain} = 0.18 \text{ mol} \times 63.55 \text{ g/mol}\)
\(\text{Mass gain} \approx 11.43 \text{ g} \)
Summary
Loss in mass at anode (Zinc): 11.77 g
Gain in mass at cathode (Copper): 11.43 g
Thus, the correct answer is: 11.77 g, 11.43 g.