All Flashcards
Define Internal Energy (U).
The total energy stored within a system, including the kinetic energy of particles and the potential energy due to interactions between them.
What is an Isovolumetric process?
A thermodynamic process where the volume remains constant (ΔV = 0).
What is an Isothermal process?
A thermodynamic process where the temperature remains constant (ΔT = 0).
What is an Isobaric process?
A thermodynamic process where the pressure remains constant (ΔP = 0).
What is an Adiabatic process?
A thermodynamic process where there is no heat transfer (Q = 0) between the system and its surroundings.
Define the First Law of Thermodynamics.
The change in internal energy (ΔU) of a closed system equals the heat added (Q) to the system plus the work done (W) on the system: ΔU = Q + W.
How do you calculate work done by a system?
W = -PΔV, where P is pressure and ΔV is the change in volume. Note the negative sign; work done by the system is negative.
How do you calculate the change in internal energy using the First Law of Thermodynamics?
ΔU = Q + W, where ΔU is the change in internal energy, Q is the heat added to the system, and W is the work done on the system.
How do you determine work done from a PV diagram?
The absolute value of the work done equals the area under the PV curve. Pay attention to the direction: increasing volume (expansion) means negative work (work done by the system), and decreasing volume (compression) means positive work (work done on the system).
What is the effect of adding heat to a closed system at constant volume?
The internal energy of the system increases (ΔU = Q), and the temperature rises.
What is the effect of compressing a gas adiabatically?
The temperature of the gas increases because work is done on the gas, increasing its internal energy.
What happens to the internal energy of an ideal gas during an isothermal expansion?
The internal energy remains constant (ΔU = 0) because the temperature is constant.
What happens to the temperature of a gas if it expands adiabatically?
The temperature decreases because the gas does work on its surroundings, reducing its internal energy.