What is the formula for Charles's Law?

Charles's Law states that the volume of a gas is directly proportional to its temperature, at constant pressure.

Charles's Law can be expressed mathematically as \( V \propto T \) or \( \frac{V_1}{T_1} = \frac{V_2}{T_2} \), where \( V \) represents the volume of the gas and \( T \) represents its temperature in Kelvin. This means that if the temperature of a gas increases, its volume increases as well, provided the pressure remains constant. Conversely, if the temperature decreases, the volume decreases.

To understand this better, imagine a balloon filled with air. If you heat the balloon, the air particles inside gain energy and move faster. This increased movement causes the particles to push outwards more forcefully, making the balloon expand. If you cool the balloon, the particles lose energy and move more slowly, causing the balloon to shrink.

It's important to note that the temperature must be measured in Kelvin for Charles's Law to apply correctly. The Kelvin scale starts at absolute zero, the point at which particles have minimal thermal motion. To convert from Celsius to Kelvin, you simply add 273.15 to the Celsius temperature.

For example, if a gas has a volume of 2 litres at 300 K and you want to find its volume at 350 K, you can use the formula \( \frac{V_1}{T_1} = \frac{V_2}{T_2} \). Plugging in the values, you get \( \frac{2}{300} = \frac{V_2}{350} \). Solving for \( V_2 \), you find that the new volume is approximately 2.33 litres.

Understanding Charles's Law helps explain everyday phenomena, such as why a football left outside on a cold day appears deflated. The lower temperature reduces the volume of the air inside the ball, making it seem less inflated.