Physical Changes

Question 1

Explain changes of state?

Answer 1

Materials can change from one state of matter to another eg water from liquid to solid when it freezes - physical change because particles are the same but arrangement and energy changes

Melting, boiling, subliming all types of physical change
Happen when heat energy is applied to a material

Change in state doesn’t change mass only a change in heat energy

Question 2

6 changes of state?

Answer 2

1 solid is heated and particles gain more energy
2 this makes particles vibrate and weakens forces holding them together and solid expands
3at certain temperature particles break free - melting - solid turns to liquid
4 liquid is heated again- particles get more energy
5 this energy make particles move faster which weakens force holding liquid together
6 at certain temperature particles have enough energy to break forces - boiling - liquid turns to gas

Question 3

Explain how materials lose energy as they cook?

Answer 3

1. Condensing and freezing are reverse of boiling and melting
2. Both are types of physical change with heat being given out
3. When substance is cooled it’s particles bind together tighter
   Forces of attraction between them get stronger pulling them together
4. If cooled enough gas will condense into liquid and liquid freeze to solid

Question 4

What do heating and cooling curves show

Answer 4

They show the energy changes that happen when a substance changes state

1. Heating graph has upward pointing lines showing temperature increasing
2. When a substance is melting or boiling the lines flatten out as heat energy is used to weaken particles rather than raising temperature
3. Cooling graph is downward sloping showing decreasing temperature
4. When a substance is cooled the graph shows flat at condensing and freezing points as forces between particles get stronger when a gas condenses or a liquid freezes so heat is given out. So. Temperature doesn’t drop until all substance has changes state.