Principle

Heat is added to a gas in a glass vessel by an electric heater which is switched on briefly. The temperature increase results in a pressure increase, which is measured with a manometer. Under isobaric conditions a temperature increase results in a volume dilatation, which can be read from a gas syringe. The molar heat capacities Cv and Cp are calculated from the pressure or volume change.

Benefits

• Determination of cp and cv
• For both demonstration and student experiments
• Suitable for many different gases

Tasks

Determine the molar heat capacities of air at constant volume Cv and at constant pressure Cp.

Learning objectives

• Equation of state for ideal gases
• First law of thermodynamics
• Universal gas constant
• Degree of freedom
• Mole volumes
• Isobars
• Isotherms
• Isochors and adiabatic changes of state