Charles's Law states that the volume of a gas is directly proportional to its temperature when pressure is held constant. The formula is:
$$\frac{V_{1}}{T_{1}} = \frac{V_{2}}{T_{2}}$$
Therefore, to find the final volume (V₂):
$$V_{2} = \frac{V_{1}}{T_{1}} \times T_{2}$$
Example: If the initial volume (V₁) is 5.0 L at 300 K (T₁), and the final temperature (T₂) is 350 K, then:
$$V_{2} = \frac{5.0}{300} \times 350 = 5.833 \text{ L}$$