The number of Faradays(F) required to produce `20g` of calcuim from molten `CaCl_2` (Atomic massof `Ca=40 gmol^-1`) is:

Options

A. `1`
B. `2`
C. `3`
D. `4`

Answer

To determine the number of Faradays (F) required to produce 20 g of calcium from molten CaCl₂, we can follow these steps:

### Step 1: Calculate the number of moles of calcium (Ca)
The atomic mass of calcium (Ca) is given as 40 g/mol. We can calculate the number of moles using the formula:

\[ \text{Number of moles} = \frac{\text{Given mass}}{\text{Molar mass}} \]

Substituting the values:

\[ \text{Number of moles of Ca} = \frac{20 \, \text{g}}{40 \, \text{g/mol}} = 0.5 \, \text{mol} \]

### Step 2: Determine the charge of calcium ions
In CaCl₂, calcium has a +2 charge because it loses two electrons to form Ca²⁺ ions. Therefore, for every mole of calcium produced, 2 moles of electrons are required.

### Step 3: Calculate the total charge in Faradays
Since 1 mole of electrons corresponds to 1 Faraday, the number of Faradays required for 0.5 moles of calcium can be calculated as follows:

\[ \text{Faradays required} = \text{Number of moles of Ca} \times \text{Charge per mole of Ca} \]

Given that each mole of Ca requires 2 Faradays:

\[ \text{Faradays required} = 0.5 \, \text{mol} \times 2 \, \text{F/mol} = 1 \, \text{F} \]

### Conclusion
The number of Faradays required to produce 20 g of calcium from molten CaCl₂ is **1 Faraday**.

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