Particle Model of Matter

Question 1

What is the formula for density

Answer 1

Density=Mass/Volume

Question 2

What are the units of density

Answer 2

kg/m^3

Question 3

What are the three states of matter

Answer 3

Solid, liquid and gas

Question 4

For each state of matter describe the arrangement of particles

Answer 4

Solid-Strong forces of attraction hold the particles close together in a fixed regular arrangement and they vibrate around their fixed points
Liquid-Weaker forces of attraction. Particles are close together but can move past each other and form irregular arrangements
Gas-Almost no forces of attraction. Particles are free to move and travel in random directions.

Question 5

Describe how you could find the volume of an irregular solid object

Answer 5

Submerge it in a eureka can filled with water so that the water displaced by the object will be transferred to the measuring cylinder

Question 6

Briefly describe an experiment to find the density of a liquid

Answer 6

Record mass of 10ml and keep pouring another 10ml recording total volume and mass each time. Then calculate an average of all calculated densities.

Question 7

What is internal energy

Answer 7

The energy stored in a system by its particles. Total energy that its particles have in their kinetic and potential energy stores

Question 8

What happens to the particles in a substance when the substance is heated

Answer 8

Energy is transferred to its particles increasing the internal energy. This leads to a change in temperature or a change in state

Question 9

Name the five changes of state

Answer 9

Melting-Solid to liquid
Boiling or evaporating-Liquid to gas
Condensing-Gas to liquid
Freezing-Liquid to solid
Sublimating-Solid to gas

Question 10

Is a change of state a physical or chemical change

Answer 10

A physical change as you don’t end up with a new substance but the same substance in a different form

Question 11

Explain the cause of the flat sections on a graph of temperature against time for a substance being heated

Answer 11

When a substance is melting or boiling you’re still putting in energy and increasing internal energy however the energy is used in breaking intermolecular bonds rather than raising temperature.

Question 12

Define specific latent heat

Answer 12

Amount of energy needed to change 1kg of it from one state to another without changing its temperature

Question 13

Give a formula for specific latent heat

Answer 13

Energy = Mass x specific latent heat

Question 14

Explain how a gas in a sealed container exerts a pressure on the walls of the container

Answer 14

Gas particles move about at high speeds and when they collide with something they exert a force on it. In a sealed container the outward gas pressure is the total force exerted by all of the particles in the gas on a unit area of the container walls.

Question 15

A sealed container of gas is kept at a constant volume. The gas is heated, what happens to the pressure of the gas and why

Answer 15

Increasing the temperature of the gas will increase the speed of the particles therefore the pressure increases as they move faster and have more frequent collision

Question 16

For a fixed mass of gas at a constant temperature what is the relationship between pressure and volume

Answer 16

Increasing the volume of a gas means the particles get more spread out and hit the walls of the container less often so the gas pressure decreases. Pressure and volume are inversely proportional

Question 17

A balloon containing a fixed mass of helium gas is moved from an area of high atmospheric pressure to one of low atmospheric pressure. What will happen to the volume of helium in the balloon

Answer 17

As atmospheric pressure decreases the pressure outside the balloon decreases therefore the balloon will expand until the pressure inside drops to the same as the atmospheric pressure

Question 18

Explain why blowing up a football with a pump causes a ball to warm up

Answer 18

The gas applies pressure to the plunger of the pump and exerts a force on it. Work has to be done against this force to push down the plunger. This transfers energy to the kinetic energy stores of the gas particles increasing its temperature.