Calculate the work done during the process when one mole of gas is allowed to expand freely into vacuum.

Explanation

To calculate the work done when one mole of gas expands freely into a vacuum, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Process**: When one mole of gas expands into a vacuum, it is undergoing a free expansion. In this scenario, there is no opposing pressure acting on the gas.

2. **Identify External Pressure**: In a vacuum, the external pressure is considered to be zero (P_external = 0). This is because there are no particles in the vacuum to exert pressure against the gas.

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