Question

For an ideal gas, enthalpy is a function of:

• A. Pressure
• B. Temperature only
• C. Volume
• D. Entropy

Hint:

For real gases, enthalpy can depend on both temperature and pressure. However, for ideal gases, it is only dependent on temperature.

Answer 1

The Correct Option is B

For an ideal gas, the enthalpy (\( H \)) is only a function of temperature. This is because the internal energy of an ideal gas depends only on temperature, and the enthalpy is the sum of internal energy and \( pV \) (pressure-volume) work. Since the equation for an ideal gas is \( pV = nRT \), where \( p \) is pressure, \( V \) is volume, and \( R \) is the gas constant, the enthalpy expression for an ideal gas is: \[ H = U + pV = nC_p T \] Where \( C_p \) is the heat capacity at constant pressure, and \( T \) is the temperature. Hence, the enthalpy is directly related to the temperature and not to pressure or volume. Therefore, temperature only is the correct answer.
- Pressure: While pressure affects the state of the gas, it does not directly influence the enthalpy in the case of ideal gases.
- Volume: Volume is also related to the state of the gas but does not affect the enthalpy directly for ideal gases.
- Entropy: Entropy is a state function but does not determine the enthalpy of an ideal gas.
Thus, the correct answer is temperature only.