Particle model of the matter

Question 1

What are the characteristics of a solid?

Answer 1

> Strong forces of attraction, which holds them together
Fixed position and definite: volume + shape.
Regular lattice, particle vibrate.

Question 2

How does a solid become liquid when heated?

Answer 2

Heat up solids:
>Particles vibrate vigorously
>At the melting point, bond break free and become liquids

Question 3

What are the characteristics of a Liquid?

Answer 3

> Weak forces of attraction, which are free to move
Definite volume
Overall shape can change

Question 4

How does a Liquid become a gas when heated?

Answer 4

Heat up liquids
>Particles gain energy and vibrate more
>At the boiling point, bonds break free

Question 5

How are the characteristics of a gas particle?

Answer 5

> Very weak forces of attraction
Free to move
No definite shape/volume
In a closed system mass won’t change.

Question 6

When the gas in a container with a fixed volume is heated, the pressure increases as the temperature increases.
Explain why the pressure increases.

Answer 6

At higher temperatures particles have more kinetic energy.
(so) the (average) speed of the particles increases.
(so there are) more frequent collisions with the wall of the container.
which apply a greater force on wall of container (so pressure rises).

Question 7

One kilogram of a gas has a much larger volume than one kilogram of a solid.
Use kinetic theory to explain why.

Answer 7

There are strong forces (of attraction) between the particles in a solid.
(holding) the particles close together
but in a gas the forces between the particles are negligible
so the particles spread out

Question 8

Explain, in terms of the particles in a liquid, why evaporation causes cooling.

Answer 8

Particles with most energy evaporate
These particles escape from the (surface of the) liquid.
Decreasing mean energy of particles (left in liquid).
Which lowers the temperature.

Question 9

The internal energy of the air increases as the tyre is inflated.
Explain why.

Answer 9

Work is done on the air .
so the temperature (of the air) increases.

Question 10

The temperature of the helium in the balloon was increased.
The mass and volume of helium in the balloon remained constant.
Explain why the pressure exerted by the helium inside the balloon would increase.

Answer 10

Particles would have a higher kinetic energy
Increased number of collisions with the walls of the balloon per second
greater forces exerted in collisions
greater force exerted on same area

Question 11

What is Internal Energy?

Answer 11

> Its the energy stored in a system by the atoms and molecules that make up the system
Total kinetic energy + Potential energy = Internal Energy

Question 12

What does heating a system do?

Answer 12

• Heating increases the energy the particles have
• This increases the internal energy
  o This either raises the temperature of the system
  o Or produces a change of state

Question 13

What is Specific Latent Heat?

Answer 13

The amount of energy needed to change the state of 1kg of a substance without a change in temperature

Question 14

What is Specific Latent heat of fusion?

Answer 14

> Energy to melt/freeze

Question 15

What is Specific Latent heat of Vaporisation?

Answer 15

> Energy to boil/condense

Question 16

What is the formula for Specific Latent Heat?

Answer 16

energy for a change of state = mass × specific latent heat
E=ML
J Kg J/Kg

Question 17

Temperature of Ice Graph description:

Answer 17

At A it is Solid.
- At B, reaches 0°C .
- From B to C there is no temperature change because the
energy is used through melting.
- From C to D it is in liquid state.
- From D to E the water is boiling. This takes longer,
because evaporation takes more energy
- From E to F the gas is heating.

Question 18

Gas and Pressure?

Answer 18

• The molecules of a gas are in constant random motion. The temperature of the gas is related
  to the average kinetic energy of the molecules.
• The higher the temperature, the greater the average kinetic energy and so the faster the
  average speed of the molecules.

Question 19

Pressure and Gas?

Answer 19

When the molecules collide with the wall of their container they exert a force on the wall.
The total force exerted by all of the molecules inside the container on a unit area of the walls is the gas pressure.
- Changing the temperature of a gas, held at constant volume, changes the pressure exerted
by the gas (known as the Pressure law).