EXPERIMENT 5 IDEAL GAS LAW : CHARLES’S LAW OBJECTIVE: Upon completion of the experiment, students should be able: 1. To measure the volume of a fixed quantity of air as the temperature changes at constant pressure. 2. To verify Charles’s Law. INTRODUCTION: Jacques Charles observed that for a fixed quantity of gas, the volume at constant pressure changes when temperature changes: the volume increases (V↑) when the temperature increases (T↑); the volume decreases (V↓) when the temperature decreases (T↓). Although first described by Charles in 1787, it was not until 1802 that Joseph Gay-Lussac expressed the relationship mathematically. Charles’s Law states that when the pressure is held constant, the volume of a fixed mass of ideal gas is in direct proportion to the temperature in degrees Kelvin. Charles’s Law can be written mathematically as follows: 1. V = k * T or V / T = k Where V is the volume of the gas, T is the temperature in degrees Kelvin, and k is a constant that depends on the pressure and amount of gas. The direct relationship is clear by looking at the equations. If a sample of gas at a fixed pressure has its temperature doubled, the volume in turn is doubled. Conversely, decreasing the temperature by one half brings about a decrease in volume by one- half.