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Flashcards in thermal Deck (17):

1 mole

the amount of material so the number of basic particles is 6*10^23 (avogadro's constant)


molar mass

mass of 1 mole of a substance


kinetic model of an ideal gas

the volume of particles negligible compared to volume occupied by gas
forces between particles 0 except during collisions
negligible time in collisions compared to between
random movement
obey newton's laws (constant velocity between)
elastic collisions (no energy lost)


ideal gas equation

PV=nRT (Pressure, Volume by gas, n moles, R gas constant, T temperature in K



force per unit area


brownian motion

evidence for the behaviour of an ideal gas
particles are seen to be moving randomly, the change in momentum after collisions with the wall shows a force acting (Newton 2), collisions experienced as an average pressure


macroscopic concepts of thermal physics

temperature, internal energy and thermal energy


thermal energy

transfer of random kinetic energy between objects as a result of a difference in temperature (energy leaking into/out of objects)
result of collisions of molecules
kinetic energy is shared out by collisions averaging the thermal energy



measure of heat, depends on the kinetic energy of particles
determines the direction of thermal energy transfers


internal energy

total potential(due to attractive forces) and random kinetic energy added up over all the individual molecules of an object
depends on substance, temperature, pressure and state of the material


phase changes

happens when the particle bonds change
when the bonds break, they immediately reform but with different particles
the higher the temperature, the faster the particles vibrate, and more often that one breaks


boiling vs evaporating

evaporation is at the surface when individual particles have enough energy to separate (causes cooling, at greatest rate at larger surface areas, high temp and low surrounding humidity)
boiling is when it happens to large numbers of particles


temperature not changing in a phase change

since temperature is the measure of average kinetic energy, at the boiling point the energy supplied does not increase the Ek, but only increases the Ep (distance) between the molecules


thermal capacity

the heat required to change the temp of a body by 1K


specific heat capacity

heat needed to raise the temp of 1 kg of material by 1K


measuring specific heat capacities

direct (using a heater and thermometer)
method of mixtures (using a mixture of two liquids to create desired one, with one known specific heat capacity, the resulting average can be used to find the other


specific latent heat

the heat needed to change 1kg of a material from one phase to another