Molecules and matter

What is internal energy?

Total amount of kinetic energy and chemical potential energy of all the particles in the system.

What happens when energy is given to raise the temperature?

Particles gain kinetic energy

What is specific heat capacity? (SHC)

The amount of energy required to raise 1kg of a substance by 1°C

What is the SHC of water?

4200J/kg°C

What is specific latent heat?

The amount of energy required to change the state of 1kg of a substance without changing its temperature

Define latent heat of fusion

the amount of energy needed to melt or freeze

Define latent heat of vaporisation

the amount of energy needed to boil or condense

What will changing the internal energy of a material do?

• Change temperature (SHC)

• Change state (SLH)

What is the relationship between volume and the pressure of a gas?

inversely proportional- as volume increases, pressure decreases

What is the relationship between temperature and the pressure of a gas?

Directly proportional

↳ Increasing temperature → increase kinetic energy of the particles

↳ Lead to increased frequency of collisions against the walls of the container

↳ Collisions exert a force

↳ more force=more pressure

What happens if a gas is squashed at a constant temperature

Increases the number of collisions per second

↳ Force per collision dosen't change because the temperature is the same

Why does increasing the volume of a containing decrease the pressure?

Particles have more space to move around so there are less collisions per second with the walls of the containiner. Collisions exert a force and since there are less collisions per second, the force per unit area decreases and therefore, so does pressure.

What is work? What does it do to a gas?

Work- the transfer of energy by a force

↳ On a gas: increases the internal energy and can cause an increase in the temperature of the gas

Why does a bicycle pump doing work on an enclosed gas lead to a temperature increase of the gas?

When work is done on the gas, it compresses it. This decreases the volume and increases the energy transferred to the gas particles: this increases the internal energy of the gas leading to an increase in temperature