1
AQA A-LEVEL PHYSICS PAPER2 EXAM ACTUAL
QUESTIONS AND CORRECT ANSWERS ALREADY
GRADED A+ GUARANTEED SUCCESS
What is the second law of thermodynamics?
thermal energy moves from regions of higher to lower temperature
What is the lowest temperature possible?
absolute zero.
0K or -273.15℃
an object at absolute zero has zero internal energy
What is the third law of thermodynamics?
absolute zero cannot be reached, and so internal energy cannot be zero
Can you define and measure specific heat capacity?
energy required to raise the temperature of 1kg of a substance by 1 degree
high SHC: heats and cools slowy
low SHC: heats and cools quickly
Can you define latent heat?
energy required to change the state of 1kg of a mass without any change of
temperature
SLH of fusion (melting)
SLH of vaporisation (boiling)
What is thermal equilibrium?
, 2
two objects are said to be in thermal equilibrium when there is no net transfer of
heat energy between them
this will only occur if both objects are at the same temperature
What is the zero law of thermodynamics?
if A is in thermal equilibrium with B, B is in thermal equilibrium with C...
then A is in thermal equilibrium with C
What is the first law of thermodynamics?
the internal energy of a system can only change by exchanging energy with its
surroundings, either by doing work or by heating
SLH fusion << SLH vaporisation, must completely separate molecules so there are
no forces of attraction
Can you measure latent heat?
Can you explain why the temperature of a substance stays steady when it is
changing state?
energy is used to break bonds between molecules for phase change to occur, not
increase KE
Boyle's law
P1V1=P2V2
pressure and volume are inversely related when temperature is constant
V decreases, more particles / unit volume => more collisions => higher force =>
higher pressure
Charles' law
V1/T1=V2/T2
volume proportional to temperature, pressure constant
temperature increases => KE increases => particles can move further and faster
Pressure law
P1/T1 = P2/T2
, 3
pressure proportional to temperature, volume constant
temp increases => KE increases => more frequent collisions => higher force, same
SA => higher pressure
Gas laws
experimental relationship between P, V, T
fixed mass of gas
empirical in nature (come from experimental evidence)
Ideal gas equation (moles)
gas laws combine to pV/T = k
k dependent on moles of gas => pV/T = nR
where n is number of moles, R is molar gas constant
Avogadro's number
number of representative particles in a mole
6.02 x 10^23
Ideal gas equation (molecules)
use pV = nRT with avogadro's number
k = R / AN => Boltzmann constant
Molar mass
the mass of one mole of a pure substance in grams
mass = mr (relative molecular mass) x mol
Relative molecular mass
= mass of a single molecule of a compound
, 4
sum of the relative atomic masses of the atoms presents within the compound
Work done on a gas
work is done on a gas to change its volume when at constant pressure
Brownian motion
= chaotic movement of colloidal particles, caused by collisions with particles of the
solvent in which they are dispersed
proves existence of atoms because they are what collide with the larger particles,
causing its path to change
Kinetic theory assumptions
- gases are in constant random motion and collisions are perfectly elastic
- collision duration is negligible compared to time between collisions
- motion follows Newton's laws
- no IM forces
- molecules move in straight lines
Ideal gas
a hypothetical gas that perfectly fits all the assumptions of the kinetic-molecular
theory
only perfectly elastic collisions between the gas molecules => no intermolecular
forces act between molecules => no potential energy => internal energy is only
sum of KEs
RMS speed
= speed of a molecule which has the average kinetic energy
more representative of maxwell's speed distribution, average velocity would be 0
find the mean of the squares
AQA A-LEVEL PHYSICS PAPER2 EXAM ACTUAL
QUESTIONS AND CORRECT ANSWERS ALREADY
GRADED A+ GUARANTEED SUCCESS
What is the second law of thermodynamics?
thermal energy moves from regions of higher to lower temperature
What is the lowest temperature possible?
absolute zero.
0K or -273.15℃
an object at absolute zero has zero internal energy
What is the third law of thermodynamics?
absolute zero cannot be reached, and so internal energy cannot be zero
Can you define and measure specific heat capacity?
energy required to raise the temperature of 1kg of a substance by 1 degree
high SHC: heats and cools slowy
low SHC: heats and cools quickly
Can you define latent heat?
energy required to change the state of 1kg of a mass without any change of
temperature
SLH of fusion (melting)
SLH of vaporisation (boiling)
What is thermal equilibrium?
, 2
two objects are said to be in thermal equilibrium when there is no net transfer of
heat energy between them
this will only occur if both objects are at the same temperature
What is the zero law of thermodynamics?
if A is in thermal equilibrium with B, B is in thermal equilibrium with C...
then A is in thermal equilibrium with C
What is the first law of thermodynamics?
the internal energy of a system can only change by exchanging energy with its
surroundings, either by doing work or by heating
SLH fusion << SLH vaporisation, must completely separate molecules so there are
no forces of attraction
Can you measure latent heat?
Can you explain why the temperature of a substance stays steady when it is
changing state?
energy is used to break bonds between molecules for phase change to occur, not
increase KE
Boyle's law
P1V1=P2V2
pressure and volume are inversely related when temperature is constant
V decreases, more particles / unit volume => more collisions => higher force =>
higher pressure
Charles' law
V1/T1=V2/T2
volume proportional to temperature, pressure constant
temperature increases => KE increases => particles can move further and faster
Pressure law
P1/T1 = P2/T2
, 3
pressure proportional to temperature, volume constant
temp increases => KE increases => more frequent collisions => higher force, same
SA => higher pressure
Gas laws
experimental relationship between P, V, T
fixed mass of gas
empirical in nature (come from experimental evidence)
Ideal gas equation (moles)
gas laws combine to pV/T = k
k dependent on moles of gas => pV/T = nR
where n is number of moles, R is molar gas constant
Avogadro's number
number of representative particles in a mole
6.02 x 10^23
Ideal gas equation (molecules)
use pV = nRT with avogadro's number
k = R / AN => Boltzmann constant
Molar mass
the mass of one mole of a pure substance in grams
mass = mr (relative molecular mass) x mol
Relative molecular mass
= mass of a single molecule of a compound
, 4
sum of the relative atomic masses of the atoms presents within the compound
Work done on a gas
work is done on a gas to change its volume when at constant pressure
Brownian motion
= chaotic movement of colloidal particles, caused by collisions with particles of the
solvent in which they are dispersed
proves existence of atoms because they are what collide with the larger particles,
causing its path to change
Kinetic theory assumptions
- gases are in constant random motion and collisions are perfectly elastic
- collision duration is negligible compared to time between collisions
- motion follows Newton's laws
- no IM forces
- molecules move in straight lines
Ideal gas
a hypothetical gas that perfectly fits all the assumptions of the kinetic-molecular
theory
only perfectly elastic collisions between the gas molecules => no intermolecular
forces act between molecules => no potential energy => internal energy is only
sum of KEs
RMS speed
= speed of a molecule which has the average kinetic energy
more representative of maxwell's speed distribution, average velocity would be 0
find the mean of the squares
