Thermal Flashcards
What’s a closed system?
System where no transfer of matter
When is internal energy constant?
When heating isn’t changed
What does increases in temperature equal?
Increase in internal energy
What does boyles law state?
At constant temp, pressure and volume of a gas are inversely proportional (pv is constant)
What does Charles law state?
At constant pressure, volume of a gas is directly proportional to its absolute temperature (V/T is constant)
What does pressure law state?
At constant volume, pressure of an ideal gas is directly proportional to its absolute temperature (P/T is constant)
What does number of molecules (N) equal?
N = n x Na
What does K equal?
K = R/Na
What is the area under a PV graph?
Work done for a gas to expand/contract
What is Brownian motion?
The random zigzag motion of an object suspended in a fluid
What is specific heat capacity?
The amount of energy needed to raise the temperature of a 1kg of a substance by 1k without changing its state
What is specific latent heat?
The energy needed to be gained/lost to change the state of 1kg of a substance without changing its temperature
Heat transfer?
Hot to cold (particles with more energy transfer it to ones with less
Higher temp difference = faster transfer
What changes or stays constant when changing state?
KE is constant by potential energy changes (bonds broken = potential increases)
What are the assumptions in kinetic theory?
- molecules have negligible volume compared to the volume of the container
- Newtonian laws apply
- force acting in a collision acts for a small time compared to the time between collisions
- collisions are perfectly elastic
- all molecules are identical
- molecules move with random motion
- molecules move in straight lines between collisions
- the gas contains lots of molecules
What is the root mean square speed?
The typical speed of molecules
Learn derivation for ideal gas pressure and kinetic energy
Have fun wanker
What happens if temp increases?
Average speed increases, increasing rate of change of momentum of molecules colliding with the container, increasing the force on walls
What happens if temp increases at constant volume?
Pressure increases because:
1) the number of collisions increases
2) larger change in momentum and therefore larger force on walls
What happens if temp increases at fixed pressure?
Volume increases because:
1) larger volume means greater time between collisions and so rate of change of momentum and force on walls increases
2) therefore volume increases and so surface area increases. The increase in area stops pressure increases
Appreciate development of gas theories
1) Greeks has similar ideas about gases
2) then boyles law
3) then Charles law
4) pressure law discovered (amontons)
5) boyles law explained by Bernoulli
6) 1827, Brownian motion
