Thermodynamics Flashcards
Topic 16
What is a thermodynamic system?
an assembly of an extremely large number of particles such that the system has its own value of pressure, volume, temperature, etc.
What is a thermodynamic process?
a process where the thermodynamic variables (P, V, T, etc.) change with time:
1. isothermal process
2. isochoric process
3. adiabatic process
What is an isothermal process?
a thermodynamic process where temperature remains constant
What is an isochoric process?
a thermodynamic process where volume remains constant
What is an adiabatic process?
a thermodynamic process where there is no heat exchange between the system and its surroundings
What is internal energy?
it is determined by the state of the system and can be expressed as the sum of a random distribution of kinetic and potential energies associated with the molecules of a system
Internal energy = KE + PE
What is the sign convention for the quantities U, Q and W?
+U –> increase in internal energy
-U –> decrease in internal energy
+Q –> heat added to the system
-Q –> heat given out by the system
+W –> work done on the system
-W –> work done by the system
For a gas doing work by expansion, what is its change in internal energy?
ΔW = PΔV
ΔU = Q + PΔV
A rise in temperature of an object leads to an ________ in its internal energy.
increase
Explain why a gas heats up as you compress it
Explain why a gas cools when it expands
Give the equation of the first law of thermodynamics
ΔU = Q + W
