physics : particle model of matter paper 1

How are solids arranged?

They are very close together. Arranged in a regular pattern. Vibrate but don’t move from place to place.

Describe how liquids are arranged.

Particles are close together. They are not arrange in a regular pattern. Particles can move around each other.

Describe how a gas is arranged.

Particles are very far apart. They are not arranged in any pattern. Particles are moving very rapidly.

How do you calculate density?

Mass / Volume

what density do solids have?

A high density. Particles are packed closely together, solids have a lot of mass for their volume.

What is the density of a liquid.

Usually a high density. Particles are close together, liquids have a lot of mass for their volume.

Describe the density of gas.

Low density. Particles very far apart so gases only have a small mass for their volume.

What solid has a different density to the usuals?

Polystyrene is a solid but has a low density. It has an open structure and many air spaces. So it has a small mass for its volume.

How do you measure the density of a regular object?

Use a balance to find the mass of the object.

Use a ruler to find the volume (length x width x height)

Calculate using mass/volume.

How do you measure the density of an irregular object?

Find the mass of the object using a balance.

Fill Eureka can with water that is reaching the spout.

Place object into the water, with a measuring cylinder under to catch the water that is displaced (volume of displaced water).

Calculate the density using mass/volume.

What method is used to find the density of an irregular object.

Displacement

What energy do particles have?

Kinetic and potential energy (intermolecular forces and chemical bonds,)

What is the internal energy?

Energy stored in a system by the particles.

It’s the total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system.

What happens to the internal energy when heating a solid/liquid

It increases the internal energy.

What happens to the internal energy when we cool a gas/liquid down?

Reduce the internal energy.

What is sublimation?

When a solid turns directly into a gas.

What is an example of something sublimating?

Carbon dioxide at room temperature in pressure.

What happens to the mass when changing state?

Mass is conserved (stays the same).

Are changes of state physical changes or chemical changes. Why?

Physical changes. We can reverse the change and the material recovers its original properties.

Why doesn’t all the liquid turn into a gas when evaporating?

Only particles on the surface have enough energy to turn into a gas.

What is the definition of specific heat capacity?

The specific heat capacity of a substance is the amount of energy required to raise the temperature of 1kg of a substance by 1c

How do you convert from joules to kilojoules?

Divide by 1000.

What is the energy needed for a substance to change state called?

Latent heat

Why does the temperature remain constant when a substance changes state?

Energy that we are putting in is weakening or breaking the forces of attraction between the particles.

What is the specific latent heat?

The amount of energy required to change the state of one kilogram of a substance with no change in temperature.

What is the specific latent heat of fusion?

Energy required to change 1kg of a solid to a liquid with no change in temperature.

What is the specific latent heat of vaporisation?

The energy required to change 1kg of a substance from a solid to a vapour with no change in temperature.

How do you increase the pressure of a gas?

Increase the number of collisions per second or the energy of each collision → increase the temperature.

What gas collisions like at a high temperature?

Particles have higher kinetic energy, particles are moving rapidly. There are more collisions per second. These are higher energy collisions.