P1.2 Changes of state

Question 1

What is density?

Answer 1

How much mass there is in a certain volume

Question 2

What is the law of conservation of mass?

Answer 2

No atoms are created or destroyed in a chemical reaction, instead they join together in different ways to form products

Question 3

What is temperature and what is it measured with?

Answer 3

Tells you how hot or cold something is

Measured with thermometer or temperature sensor

Question 4

What are 2 units of temperature?

Answer 4

Degrees Celsius (°C)
Kelvin (K)

Question 5

In a thermal store, what is the difference between energy and temperature?

Answer 5

• energy in a thermal store is measured in joules, it depends on particle arrangement and how fast they are moving / vibrating
• temp tells you the average kinetic energy of the particles

Question 6

Heating:

Answer 6

• change the energy stored within the system to increase the temp (ready for a hot shower)
• produce a change of state (ice melting)
• make chemical reaction happen (wood burning in a fire)

Question 7

What is a physical change? State some examples

Answer 7

• no new substances are made, easily reversed as particles are simply rearranged
• changes of state
• dissolving

Question 8

What is specific heat capacity?

Answer 8

The energy needed to raise the temperature of 1kg of a material by 1°C

Question 9

The amount of energy needed to raise the temperature of an object depends on:

Answer 9

• type of material
• mass of material
• the temperature rise

Question 10

What is internal energy?

Answer 10

The energy that relates to the motion, vibration, rotation and arrangement of the particles.

Question 11

What does heating increase in the material?

Answer 11

Internal energy

Question 12

Specific heat capacity formula

Answer 12

Change in               = mass (kg)  X specific heat         X change in temp (°C)
Thermal energy (J)                         capacity (J/kg°C)

Question 13

What does specific heat capacity tell you?

Answer 13

It tells you how resistant a material is to change in temperature

Question 14

What liquid is especially resistant to temperature change?

Answer 14

Water

• makes it good for central heating systems
• means oceans are less likely to freeze

Question 15

Change of state - gas —> liquid

Answer 15

Condensing

Question 16

Change of state - liquid —> gas

Answer 16

Evaporation

Question 17

Change of state - solid —> liquid

Answer 17

Melting

Question 18

Change of state - liquid —> solid

Answer 18

Solidifying / freezing

Question 19

Change of state - solid —> gas

Answer 19

Subliming / sublimation

Question 20

Change of state - gas —> solid

Answer 20

Depositing / deposition / re-sublimating / re-sublimation

Question 21

What is specific latent heat?

Answer 21

The amount of energy required to change the state of 1kg of a material without changing its temperature

Question 22

What is specific latent heat of fusion (or melting)

Answer 22

Energy transferred when 1kg of a substance changes from solid to liquid state, or liquid to solid state

Question 23

What is specific latent heat of vaporisation?

Answer 23

The energy transferred when 1kg of a substance changes from liquid to gas

Question 24

Specific latent heat formula

Answer 24

Thermal energy for = mass (kg) X Specific latent heat (J/kg)
a change in state

Question 25

State 1 similarity and 1 difference between specific latent heat & specific heat capacity?

Answer 25

• both involve energy changes of 1kg of a substance

- latent heat is about the changes of state, and heat capacity is about change of temperature