Question

The number of Faradays required to completely deposit magnesium from 1 L of 0.1 M MgCl\(_2\) aq. solution is:

• A. 0.2
• B. 0.1
• C. 0.3
• D. 0.4

Hint:

For calculating the number of Faradays required, use the formula: Faradays = Moles of substance \( \times \) Valency of the substance.

Answer 1

The Correct Option is A

The number of Faradays required to completely deposit a substance in an electrolysis process is given by the formula: \[ \text{Faradays} = \frac{\text{Moles of substance} \times \text{Valency}}{1} \] In this case, we are depositing magnesium from a \( 0.1 \, \text{M} \, \text{MgCl}_2 \) solution. The valency of magnesium (Mg) is 2. Step 1: Calculate moles of \( \text{MgCl}_2 \) in 1 L of solution: \[ \text{Moles of MgCl}_2 = 0.1 \, \text{mol/L} \times 1 \, \text{L} = 0.1 \, \text{mol} \] Step 2: Number of Faradays required is given by: \[ \text{Faradays} = 0.1 \, \text{mol} \times 2 \, \text{F/mol} = 0.2 \, \text{Faradays} \] Thus, the correct answer is \( 0.2 \, \text{Faradays} \).

Answer 2

Step 1: Understand the problem
We need to find the number of Faradays required to completely deposit magnesium from 1 L of 0.1 M MgCl\(_2\) solution.

Step 2: Write down known values
- Volume of solution = 1 L
- Concentration of MgCl\(_2\) = 0.1 M (moles per liter)
- Number of moles of Mg\(^{2+}\) = 0.1 moles (since 1 L × 0.1 M = 0.1 moles)

Step 3: Reaction and charge transfer
The electrodeposition of magnesium involves the reaction:
\[ \text{Mg}^{2+} + 2e^- \rightarrow \text{Mg (metal)} \]
Each mole of Mg\(^{2+}\) requires 2 moles of electrons (2 Faradays) for complete deposition.

Step 4: Calculate total Faradays required
Total moles of electrons needed = 0.1 moles Mg\(^{2+}\) × 2 moles electrons/mole Mg = 0.2 moles electrons
Since 1 Faraday corresponds to 1 mole of electrons,
Number of Faradays required = 0.2 Faradays

Step 5: Conclusion
Therefore, 0.2 Faradays are required to completely deposit magnesium from 1 L of 0.1 M MgCl\(_2\) solution.