Thermal

Question 1

Ideal gas equation

Answer 1

pV = nRT
(All KE energy, no PE energy as no interaction between particles and follows RAVED)

Question 2

First law of thermodynamics

Answer 2

∆U = Q - W
Q = heat added to the system
W = work done by the system

Work is done on water and therefore due to 1st law of thermodynamics is converted to thermal energy

Question 3

RAVED

Answer 3

Random motion
Attraction between particles is negligible
Volume is negligible
Elastic collisions
Duration of collisions is negligible

Question 4

Rms

Answer 4

Square the value
Find the mean of those value
Square root the mean

Question 5

Brownian motion

Answer 5

Random motion of particles due to collision with other fast moving particles

Question 6

Absolute zero
1) gas laws
2) kinetic theory

Answer 6

1) when pressure/volume extrapolates to zero
2) when random motion of particles stop / kinetic energy is zero

Question 7

Specific latent heat of fusion Vs vaporisation

Answer 7

Fusion = between solid and liquid
Vaporisation = liquid and gas

Question 8

Pressure law

Answer 8

P/T = constant
As P increases so does T

Question 9

Ideal gas law

Answer 9

pV/T = constant
Dependant on number of moles

Question 10

Moles equation

Answer 10

Moles = grams/rams

Question 11

What does 3RT/2Na find the KE of?

Answer 11

A molecule and therefore multiply by Na for the KE of a mole

Question 12

Formula for if 2 substances touch and reach common temperature

Answer 12

m1c1(T - T1) = m2c2(T2 - T)

Question 13

What happens when a substance is changing state

Answer 13

It breaks ‘some’ of the atomic bonds.

Question 14

What is the area of pressure against volume graph

Answer 14

P∆V = workdone

Question 15

What is emitted when a nucleus is excited and when an electron is excited?

Answer 15

1) Gamma primarily / EM waves
2) Photons (packets of EM waves)

Question 16

Explain why the molecules of gas exert a force on the walls of a container? Refer to Newton’s laws

Answer 16

Change in momentum= 2x mu
Therefore change in momentum requires force (N2)
Wall must exert force on molecule
Therefore vice versa (N3)

Question 17

Explain in terms of KE theory why a pressure is exerted by the gas on the piston?

Answer 17

Atoms collide with piston, they change direction and therefore momentum. As f = ∆(mv)/t they exert force on the piston.

Question 18

Impulse Vs force when comparing to momentum

Answer 18

Impulse is the change in momentum of an object, and force is the rate of change of momentum. Mathematically, impulse is equal to the force applied to an object multiplied by the time during which the force is applied. So, force can be expressed as the derivative of momentum with respect to time.

Question 19

When a pump is working at higher speeds why is the rise in temperature in the water it’s circulating greater?

Answer 19

Pump does work and due to 1st law of thermodynamics temperature increases

Question 20

What is an isothermal change?

Answer 20

A process that occurs at a constant temperature