Evaluate the ratio of specific heat for monoatomic diatomic and polyatomic gases at ordinary temperature
Answers
Answer:
The molar specific heat capacity of a gas at constant volume (Cv) is the amount of heat required to raise the temperature of 1 mol of the gas by 1 °C at the constant volume. Its value for monatomic ideal gas is 3R/2 and the value for diatomic ideal gas is 5R/2.
The molar specific heat of a gas at constant pressure (Cp) is the amount of heat required to raise the temperature of 1 mol of the gas by 1 °C at the constant pressure. Its value for monatomic ideal gas is 5R/2 and the value for diatomic ideal gas is 7R/2.
Monatomic Diatomic
f 3 5
Cv 3R/2 5R/2
Cp 5R/2 7R/2
γ
1.67 1.40
The specific heat at constant volume is related to the internal energy
is degrees of freedom of the gas molecule. The degrees of freedom is 3 for monatomic gas and 5 for diatomic gas (3 translational + 2 rotational). The internal energy of an ideal gas at absolute temperature.
The specific heat at constant pressure (Cp) is greater than that at constant volume (Cv). The heat given at constant volume is equal to the increase in internal energy of the gas. The heat given at constant pressure is equal to the increases in internal energy of the gas plus the work done by the gas due to increase in its volume of (Q= triangle u +triangle w)
The ratio of the specific heats, also called adiabatic index.
The ratio of the specific heats is 5/3 for monatomic ideal gas and 7/5 for diatomic gas. Its value for air is 1.4. This ratio is used to define (1) adiabatic process