Thermal Physics

Question 1

Brownian Motion

Answer 1

The random movement of microscopic particles in a fluid as a result of continuous bombardment from the molecules of surrounding medium

Question 2

Internal Energy

Answer 2

the sum f the random kinetic and potential energies of molecules in a substance

Question 3

what causes a change in internal energy

Answer 3

A rise in temperature

A change in state

Question 4

Specific Heat Capacity of a substance

Answer 4

the amount of energy required to change the temperature of 1kg of the substance by 1 degree

Question 5

0 Kelvin

Answer 5

273.15 Degrees Celsius

Question 6

Latent heat of fusion

Answer 6

the heat needed to change a mass of 1 kg of a substance from a solid to a liquid at the same temperature

Question 7

Latent heat of vaporisation

Answer 7

the heat needed to change a mass of 1kg of a substance from a liquid to a gas at the same temperature

Question 8

Boyle’s Law

Answer 8

pressure and volume are of a gas are inversely proportional when the temperature is constant

Question 9

spacing, ordering and motion of solids

Answer 9

around 1nm
they have a regular structure
vibrate around a fixed position

Question 10

spacing, ordering and motion of liquids

Answer 10

around 1nm
it has no fixed shape
molecules are free to move and move randomly

Question 11

spacing ordering and motion of gases

Answer 11

spacing is a few powers of ten larger

move in rapid random motion

Question 12

pressure

Answer 12

force per unit area

Question 13

thermal equilibrium

Answer 13

there is no net transfer of heat/ thermal energy between two objects

Question 14

Why are absolute scales used

Answer 14

They don’t depend on characteristics of any particular substance

Question 15

absolute zero

Answer 15

the temperature at which a substance has minimal internal energy

Question 16

when is E=mc∆θ used

Answer 16

to determine the c (specific heat capacity) of a substance

or find the energy required to increase the temperature of a substance

Question 17

ideal gas equation

Answer 17

pV=T

Question 18

4 assumptions of the kinetic theory model of ideal gases

Answer 18

1. elastic collisions with the walls of the container
2. forces between molecules are negligible except during collisions
3. time of collisions is much smaller that the time between collisions
4. the volume of molecules is negligible compared to the volume of the container

Question 19

what is Avagadro’s constant

Answer 19

the amount of particles which are in one mole of a substance; 6.02x10^23 particles

Question 20

what does each letter mean in pV=nRT

Answer 20

p is pressure
V is volume
n is number of moles
R is 8.31 (molar gas constant)
T is temperature

Question 21

what does each letter mean in pV=NkT

Answer 21

p is pressure
V is volume
N is number of molecules
k is 1.38x10^-23
T is temperature

Question 22

mean transational kinetic energy of atoms equation

Answer 22

E=3/2 kT