Estimaing Osmolarity by Change in Volume
Charles’s Law
Prepared by H. A. Neidig, Lebanon Valley College, and N. Spencer, Franklin and Marshall College
PURPOSE OF THE EXPERIMENT
Establish the relationship between the volume of a gas and the temperature of a gas at constant pressure. Verify Charles’s law.
BACKGROUND INFORMATION
The volume of a gas at constant pressure increases when the temperature of the gas is raised. This observation was first made by Jacques A. C. Charles in 1787. A quantitative study did not follow, however, until 1802, when Joseph L. Gay’ Lussac determined the relationship between the volume of a gas and its temperature.
The relationship between the volume and the temperature of a gas at constant pressure is known as Charles’s law. Charles’s law states that, at constant pressure, the volume of a given mass of gas is directly proportional to its Kelvin temperature. The law may be expressed mathematically as
V=kT (Eq.1)
where V is the volume, T is the Kelvin temperature of the gas, and k is a proportionality constant, which is dependent on the mass of gas and the pressure.
If the pressure and the mass of a gas are kept constant, Charles’s law may be applied at two different temperatures. In Equation 2
V1 = k and V2 = k (Eq.2) T1 T2
V1 and T1 refer to the volume at temperature T1. V2 and T2 refer to the volume at temperature T2. If conditions are chosen so that the proportionality constant is the same at both temperatures, Charles’s law may he written
V1 = V2 (Eq.3) T1 T2
Charles’s law may be verified by finding the volume occupied by a gas at two different temperatures. If the volume-to-temperature ratios are the same at both temperatures, Charles’s law is verified.
The gas you will use in this experiment is air. You will find the volume of air in an Erlenmeyer flask at two different temperatures. First, the air in the flask will be heated to the
Prepared by H. A. Neidig, Lebanon Valley College, and N. Spencer, Franklin and Marshall College
PURPOSE OF THE EXPERIMENT
Establish the relationship between the volume of a gas and the temperature of a gas at constant pressure. Verify Charles’s law.
BACKGROUND INFORMATION
The volume of a gas at constant pressure increases when the temperature of the gas is raised. This observation was first made by Jacques A. C. Charles in 1787. A quantitative study did not follow, however, until 1802, when Joseph L. Gay’ Lussac determined the relationship between the volume of a gas and its temperature.
The relationship between the volume and the temperature of a gas at constant pressure is known as Charles’s law. Charles’s law states that, at constant pressure, the volume of a given mass of gas is directly proportional to its Kelvin temperature. The law may be expressed mathematically as
V=kT (Eq.1)
where V is the volume, T is the Kelvin temperature of the gas, and k is a proportionality constant, which is dependent on the mass of gas and the pressure.
If the pressure and the mass of a gas are kept constant, Charles’s law may be applied at two different temperatures. In Equation 2
V1 = k and V2 = k (Eq.2) T1 T2
V1 and T1 refer to the volume at temperature T1. V2 and T2 refer to the volume at temperature T2. If conditions are chosen so that the proportionality constant is the same at both temperatures, Charles’s law may he written
V1 = V2 (Eq.3) T1 T2
Charles’s law may be verified by finding the volume occupied by a gas at two different temperatures. If the volume-to-temperature ratios are the same at both temperatures, Charles’s law is verified.
The gas you will use in this experiment is air. You will find the volume of air in an Erlenmeyer flask at two different temperatures. First, the air in the flask will be heated to the