Thermodynamics Flashcards
What is heat?
Energy transferred due to a temperature difference
What does heat transfer enable an object to do?
Causes the internal energy of the object to rise, or allows the object to do work
State the first law of thermodynamics
The heat energy supplied to a system either increases the internal energy of the object or enables it to do work, or both
State what the components and their relativity in the first law of thermodynamics equation
Q = delta U + W
Q - heat energy transfer due to a different temperature. Positive if heat is transferred into system
delta U - Increase in internal energy. Positive if internal energy increases
W - Work done. Positive if work is done by the system
Define internal energy
The sum of the random distribution of the kinetic and potential energies of the molecules
Why does an ideal gas not possess molecular potential energy?
Because there are no internal forces of attraction between ideal gas molecules
How do you change the temperature of a gas?
Changing the internal energy of the gas
How do you change the internal energy of a gas?
Work must be done on the gas, or heat must be transferred to or from the gas
What happens to the volume of a gas when work is done on it and why?
The volume is reduced (compressed) Work is done on it by the applied forces which push the pressure forces back
At constant volume, how much work is being done by the gas and why?
No work because the forces due to pressure in the gas do not move the container walls
When is work done by a gas and why?
When the gas expands and the forces due to the pressure push back the container walls
When is work done by a gas, and work is done on a gas?
On a gas when it is compressed
By a gas when it expands
What is the work done by a gas when its volume expands at constant pressure equal to?
W = p delta V
What is an adiabatic change?
A change that occurs without heat transfer
How can you compress a gas adiabatically?
Reduce its volume rapidly, or to insulate the gas so heat cannot transfer
