How many moles of ethyl chloride should be reacted with sodium in the presence of dry ether in order to obtain 1.12 litres of butane at STP?

Options

A. 0.5 mole
B. 0.1 mole
C. 1 mole
D. 0.25 mole

Answer

To determine how many moles of ethyl chloride (C2H5Cl) should be reacted with sodium (Na) in the presence of dry ether to obtain 1.12 liters of butane (C4H10) at standard temperature and pressure (STP), we can follow these steps:

### Step 1: Understand the Reaction
The reaction we are dealing with is the Wurtz reaction, which can be represented as follows:

\[ 2 \text{C}_2\text{H}_5\text{Cl} + 2 \text{Na} \rightarrow \text{C}_4\text{H}_{10} + 2 \text{NaCl} \]

From the equation, we see that 2 moles of ethyl chloride produce 1 mole of butane.

### Step 2: Calculate Moles of Butane
At STP, 1 mole of any gas occupies 22.4 liters. Therefore, we can calculate the number of moles of butane in 1.12 liters:

\[ \text{Moles of butane} = \frac{\text{Volume of butane}}{\text{Molar volume at STP}} = \frac{1.12 \, \text{liters}}{22.4 \, \text{liters/mole}} = 0.05 \, \text{moles} \]

### Step 3: Relate Moles of Butane to Moles of Ethyl Chloride
From the balanced reaction equation, we know that 2 moles of ethyl chloride produce 1 mole of butane. Therefore, to find the moles of ethyl chloride required, we can set up the following proportion:

\[ \text{Moles of ethyl chloride} = 2 \times \text{Moles of butane} = 2 \times 0.05 \, \text{moles} = 0.1 \, \text{moles} \]

### Conclusion
Thus, to obtain 1.12 liters of butane at STP, we need to react **0.1 moles of ethyl chloride** with sodium in the presence of dry ether.

### Final Answer
0.1 moles of ethyl chloride should be reacted.

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