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 solve the problem of how many moles of ethyl chloride (C2H5Cl) should be reacted with sodium in the presence of dry ether to obtain 1.12 liters of butane (C4H10) at STP, we can follow these steps:

### Step 1: Calculate the number of moles of butane produced
At standard temperature and pressure (STP), 1 mole of any gas occupies 22.4 liters. We need to find out how many moles of butane correspond to 1.12 liters.

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

### Step 2: Determine the stoichiometry of the reaction
The reaction between ethyl chloride and sodium in the presence of dry ether is a Wurtz reaction, which can be represented as follows:

\[ 2 \text{C2H5Cl} + 2 \text{Na} \rightarrow \text{C4H10} + 2 \text{NaCl} \]

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

### Step 3: Calculate the number of moles of ethyl chloride required
Since 2 moles of ethyl chloride yield 1 mole of butane, we can set up a ratio to find out how many moles of ethyl chloride are needed for 0.05 moles of butane:

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

### Final Answer
Therefore, the number of moles of ethyl chloride required is **0.1 moles**.

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