An ideal gas is allowed to expand from 1 L to 10 L against a constant external pressure of 1 bar. Calculate the work done inkJ.

Explanation

To calculate the work done when an ideal gas expands from 1 L to 10 L against a constant external pressure of 1 bar, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Initial volume (V1) = 1 L
- Final volume (V2) = 10 L
- External pressure (P_external) = 1 bar

2. **Convert Units:**
- Convert the pressure from bar to Pascal (since 1 bar = 10^5 Pascal).
\[ P_{\text{external}} = 1 \text{ bar} = 10^5 \text{ Pa} \]
- Convert the volumes from liters to cubic meters (since 1 L = 10^-3 m³).
\[ V1 = 1 \text{ L} = 1 \times 10^{-3} \text{ m}^3 \]
\[ V2 = 10 \text{ L} = 10 \times 10^{-3} \text{ m}^3 = 0.01 \text{ m}^3 \]

3. **Calculate the Change in Volume:**
- The change in volume (ΔV) can be calculated as:
\[ \Delta V = V2 - V1 = 0.01 \text{ m}^3 - 0.001 \text{ m}^3 = 0.009 \text{ m}^3 \]

4. **Use the Work Formula:**
- The work done (W) by the gas during expansion against a constant external pressure is given by:
\[ W = - P_{\text{external}} \times \Delta V \]
- Substitute the values into the formula:
\[ W = - (10^5 \text{ Pa}) \times (0.009 \text{ m}^3) \]
\[ W = - 900 \text{ J} \]

5. **Convert Joules to Kilojoules:**
- Since we need the answer in kilojoules, we convert joules to kilojoules:
\[ W = -900 \text{ J} \times \frac{1 \text{ kJ}}{1000 \text{ J}} = -0.9 \text{ kJ} \]

### Final Answer:
The work done by the gas during the expansion is **-0.9 kJ**.