particle model of matter

Question 1

What is density?

Answer 1

Mass per unit volume.

Question 2

What is the equation for density?

Answer 2

Mass
———
Volume

Question 3

Why do gases have the lowest density?

Answer 3

~Spacing between the atoms increase by x10
~As the particles have lots of energy to move
~This increases volume
~Which therefore decreases density

Question 4

What stays the same when evaporating, melting, condensing and freezing?

Answer 4

Mass.

Question 5

True or false? Are physical changes reversible?

Answer 5

True.

Question 6

What is internal energy stored in?

Answer 6

Particles (atoms and molecules) within a system.

Question 7

What are 2 examples of internal energy?

Answer 7

Kinetic energy and potential energy.

Question 8

What does heating increase?

Answer 8

The internal energy.

Question 9

What does internal energy do when heated?

Answer 9

Raises the temperature or produces a change of state.

Question 10

What is specific heat capacity?

Answer 10

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

Question 11

What is the equation for specific heat capacity?

Answer 11

Change in thermal energy= mass x specific heat capacity x temperature change.

Question 12

What is specific latent heat?

Answer 12

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

Question 13

What must the substance be before specific latent heat occurs?

Answer 13

At the right temperature to change state first.

Question 14

What is specific latent heat of fusion?

Answer 14

The energy to melt/freeze.

Question 15

What is specific latent heat of vaporisation?

Answer 15

The energy to boil/condense.

Question 16

What is the equation for specific latent heat?

Answer 16

Energy for a change in state= mass x specific latent heat.

Question 17

In melting and evaporating, energy is…

Answer 17

Absorbed.

Question 18

In freezing and condensing, energy is…

Answer 18

Released.

Question 19

What is sublimation?

Answer 19

When a sold goes straight to a gas eg. solid CO2.

Question 20

The higher the temperature in pressure…

Answer 20

The greater the average kinetic energy as molecules move faster.

Question 21

What happens when molecules collide with the walls of their container?

Answer 21

They exert a force on them.

Question 22

What is gas pressure?

Answer 22

The total force exerted by all the molecules in the container of a unit area.

Question 23

What is the pressure law?

Answer 23

Changing the temperature of a gas held at a constant volume changes the pressure exerted by the gas.

Question 24

What can pressure changes do to a gas?

Answer 24

Compress or expand it.

Question 25

What is Boyle’s Law?

Answer 25

Increasing the volume in which a gas is contained (at a constant temperature) can decrease pressure. (due to a reduced number of collisions per unit area)

Question 26

What is the equation for work done using pressure?

Answer 26

Pressure x volume.

Question 27

What is work done when increasing the pressure of a gas?

Answer 27

Compressing or expanding the gas (changing the volume).

Question 28

What are 2 ways of increasing the pressure of a gas?

Answer 28

~Adding more particles to fixed volume
~Keepijg a fixed number or particles but for a smaller volume