For an ideal gas, enthalpy is independent of pressure. Doesn't the open system version of the first law require you to use enthalpy?yecko said:
Is that imply enthalpy is used just because the first law of thermodynamics is applicable?Chestermiller said:
yecko said:
Yes.
The formula for calculating specific heat at constant pressure is Q = m x Cp x ΔT, where Q is the amount of heat transferred, m is the mass of the substance, Cp is the specific heat at constant pressure, and ΔT is the change in temperature.
Specific heat at constant pressure (Cp) is the amount of heat required to raise the temperature of a substance by 1 degree Celsius at constant pressure. Specific heat at constant volume (Cv) is the amount of heat required to raise the temperature of a substance by 1 degree Celsius at constant volume. Cp is typically higher than Cv because at constant pressure, the substance is allowed to expand and do work, while at constant volume, no work is done.
The units for specific heat at constant pressure are joules per kilogram per degree Celsius (J/kg°C) in the SI system and calories per gram per degree Celsius (cal/g°C) in the CGS system.
The specific heat at constant pressure varies for different substances due to differences in their molecular structure and composition. For example, substances with stronger intermolecular forces tend to have higher specific heat at constant pressure because more energy is required to break these bonds and raise the temperature.
Specific heat at constant pressure is an important factor in thermodynamics as it helps to determine the amount of heat required to increase the temperature of a substance. It is also used to calculate the heat capacity of a substance, which is necessary for determining the amount of energy needed for various processes such as heating and cooling. Additionally, specific heat at constant pressure is used in the calculation of enthalpy, a thermodynamic quantity that measures the total energy of a system.