Chapter 6: Molecules And Matter

Question 1

What is the equation for density?

Answer 1

Density = mass/ volume (kg/m3)

Question 2

What is the density triangle?

Answer 2

Mass top
Density bottom left
Volume bottom right

Question 3

What happens if an object has a lower density than water?

Answer 3

It floats on the water

Question 4

Describe the particles of a solid

Answer 4

The particles of a solid are held next to each other in fixed positions. They are the least energetic of the states of matter. They have a fixed shape and a fixed volume. They have the lowest kinetic energy of the three states of matter. They don’t move around and only vibrate, they cannot be compressed .

Question 5

Describe the particles of a liquid

Answer 5

The particles in a liquid move around at random and are in contact with each other, they are more energetic than the particles in a solid. They have the second highest kinetic energy, they move around freely but must remain within a defined space/volume. They flow and move past each other. They cannot be compressed.

Question 6

Describe the particles in a gas

Answer 6

They move about randomly and are far apart so gases are much less dense than solids and liquids. They are the most energetic and have the highest kinetic energy of all the states of matter. They move around freely without a defied space/volume. They can be compressed

Question 7

What happens to the mass when particles change state?

Answer 7

Its mass stays the same because the number of particles stays the same

Question 8

What is a pure substances melting point defined as?

Answer 8

Its melting point is the temperature at which it melts.

It is the same temperature that it solidifies

Question 9

What is a pure substances boiling point point defined as?

Answer 9

Its boiling point is the temperature at which it boils.

It is the same temperature at which it condenses.

Question 10

What is boiling?

Answer 10

It occurs throughout the liquid at its boiling point.

Question 11

What is evaporation?

Answer 11

Evaporation occurs from the surface of a liquid when its temperature is below boiling its boiling point

Question 12

What happens to a substances temperature when it is changing state?

Answer 12

It stays the same

Question 13

Wat does the flat section of a temperature time graph tell you?

Answer 13

It gives the melting point or the boiling point of a substance

Question 14

What is the difference between boiling and evaporation?

Answer 14

Evaporation happens at any temperature, boiling only happens at the substances boiling point

Question 15

What happens when you increase the temperature of a substance?

Answer 15

It increases the substances internal energy and the kinetic wnegy of its particles increases.

Question 16

What happens to the energy of the substance when it melts or boils

Answer 16

If it melts or boils the potential energy of its particles increases

Question 17

What causes the pressure of a gas?

Answer 17

The pressure of a gas on a surface is caused by the particles of the gas repeatedly hitting the surface of the container

Question 18

What is latent heat?

Answer 18

It is the energy needed for a substance to change its state without changing its temperature

Question 19

What is specific latent heat of fusion?

Answer 19

Is the energy needed to melt 1kg of substance without changing its temperature

Question 20

What is the specific latent heat of vaporisation?

Answer 20

Is the energy needed to boil 1kg of a substance without changing its temperature

Question 21

What is the internal energy of a substance?

Answer 21

It is the combination of the movement and position of the particles.
The kinetic energy they have due to movement + the potential energy they have due to their position = internal energy

Question 22

What is the equation triangle for latent heat of fusion?

Answer 22

Energy top (J)
Latent heat bottom left (J/kg)
Mass bottom right (kg)

Remember Elf massacre

Question 23

What is the triangle for latent heat of vaporisation?

Answer 23

Energy top (J)
Latent heat bottom right (J/kg)
Mass bottom left (kg)

Remember elven massacre

Question 24

What happens if the temperature of a gas in a sealed container increases?

Answer 24

The pressure increases

Question 25

Why does the pressure of a gas in a sealed container increase when it is heated?

Answer 25

• The molecules move faster so they hit the surface with more force
• The frequency of impacts per second increases so the total force of impacts increases