Thermal Physics Flashcards
what is internal energy
the sum of all the kinetic and potential energies of the particles in a substance
how is internal energy increases
energy transferred by heating
work done on object e.g. electricity
if internal energy is constant?
there is no energy transfer by heating and no work is done
OR energy transfer by heating or work done is balanced
when does an object has minimal internal energy
at 0K temp
specific heat capacity
energy needed to raise the temperature of 1kg mass by 1K
latent heat of fusion
solid becomes liquid because energy is supplied at melting point.
The energy needed to melt a solid already at melting point is the latent heat of fusion
latent heat of vaporisation
when a liquid becomes a gas, molecules gain energy to overcome bonds holding them.
the energy needed to vaporise a liquid is latent heat of vaporisation
specific latent heat equation
Q = ml
specific heat capacity equation
Q = mc∆T
Boyles law
pV = constant for contant T and m
Charles law
v/T = constant for constant m and p
Pressure law
p/T = constant for constant m and V
Ideal gas law assumptions
- Intermolecular forces are negligible except during a collision
- Volume of the molecules negligible compared to volume of gas
- Collisions between molecules and between molecules and the container
walls are perfectly elastic - Duration of a collision negligible compared to time between collisions.
- Laws of Newtonian Mechanics apply
- All molecules of a particular gas are identical
- The motion of molecules is random
- There is a large number of molecules
what is brownian motion
can be seen when smoke particles are observed with a microscope
the particles move unpredictably because they move unevenly and randomly
avogrados constant
number of atoms in 12g of carbon 12
one atomic unit
1/12 the mass of carbon 12 atom
what is molar mass
mass of 1 mol of a substance
no. of moles =
no. of moles = mass of substance/molar mass
ideal gas equations
pV = nRT
pV = NkT
