Adiabatic expansion
Definition
Adiabatic expansion is a process in which a gas expands without exchanging heat with its surroundings. During this expansion, the internal energy of the gas decreases, resulting in a drop in temperature.
5 Must Know Facts For Your Next Test
- The first law of thermodynamics for adiabatic processes is given by the equation $\Delta U = -W$, where $\Delta U$ is the change in internal energy and $W$ is the work done by the gas.
- For an ideal gas undergoing adiabatic expansion, the relationship between pressure and volume can be expressed as $PV^\gamma = \text{constant}$, where $\gamma = \frac{C_p}{C_v}$ (the heat capacity ratio).
- In an adiabatic process, there is no heat transfer ($Q = 0$), meaning all changes in internal energy are due to work done.
- The temperature of an ideal gas decreases during adiabatic expansion because its internal energy drops.
- An adiabatic process can be either reversible or irreversible; however, for ideal gases, reversible adiabatic processes are often considered due to their simplicity.
Review Questions
- What happens to the temperature of an ideal gas during adiabatic expansion?
- How does the first law of thermodynamics apply to adiabatic processes?
- What is the relationship between pressure and volume in an ideal gas undergoing adiabatic expansion?
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Related terms
Isothermal Process: A thermodynamic process that occurs at a constant temperature.
Heat Capacity Ratio (\gamma): The ratio of the specific heat at constant pressure ($C_p$) to the specific heat at constant volume ($C_v$), denoted as $\gamma = \frac{C_p}{C_v}$.
Internal Energy: The total energy contained within a system due to molecular motion and interactions.
