Thermal

Question 1

What is internal energy?

Answer 1

The sum of the potential and kinetic energies of a system.

Question 2

How can you increase the thermal energy of a system?

Answer 2

We can increase it by heating it up or doing work on the object.

Question 3

Explain the energy changes that occur during a change of state.

Answer 3

During change of state the potential energy of the particles change but the kinetic energies doesn’t change

Question 4

What is the first law of thermodynamics?

Answer 4

ΔU = Q - W

Where U = internal energy

And Q = the heat added to a system

And W is the work done by the system

Question 5

What is the specific heat capacity of substance?

Answer 5

The energy required to raise the temperature of 1kg of a substance by 1K.

Question 6

What is the specific latent heat of a substance?

Answer 6

The energy required to change the state per unit mass of a substance, while keeping the temperature constant.

Question 7

What is an ideal gas?

Answer 7

A gas that:
● The gas molecules don’t interact with each other.
● The molecules are thought to be perfectly spheres.

Question 8

What is Boyle’s law?

Answer 8

Pressure is inversely proportional to volume, providing temperature is constant.

Question 9

In an ideal gas,how would increasing the volume change the temperature of the gas, while the pressure remains constant?

Answer 9

As you increase the volume, you also increase the temperature.

Question 10

Explain how increasing the temperature of a balloon, while keeping the volume the same will increase the pressure.

Answer 10

● As the temperature increases, the average kinetic energy increases.
● Therefore the particles are travelling at a higher speed on average
● There are also more frequent collisions
● Which means the particles would exert a greater force
● Which would cause a increased rate of change of momentum
● Therefore increasing pressure

Question 11

What is absolute zero?

Answer 11

At - 273℃
This is where objects have no/minimum kinetic energy.

Question 12

What is Avogadro’s constant? (in words)

Answer 12

The number of atoms there are in one mole of a substance.

Question 13

True or false. ‘All collisions between particles and between particles and the wall are elastic’ is an assumption of an ideal gas?

Answer 13

True.

Question 14

State an assumption of an ideal gas related to time?

Answer 14

The time for each collisions is negligible in comparison to the time take between collisions.

Question 15

Describe 3 other assumptions of the ideal gas equation.

Answer 15

● The particles move randomly
● They follow Newton’s laws of motion
● No intermolecular forces act between particles

Question 16

Brownian Motion?

Answer 16

Brownian motion is the idea that very small objects have random motion in a liquid or gas due to random bombardment by the molecules in this substance. This movement will be fractionally more on one side than the other so a force will push it for an instant as the net forces shifts directions. This random motion is Brownian Motion and gives evidence for the existence of atoms.