1. Changes In States

2. Melting
To explain the movement of particles in the process of _____________.
 Melting
 (a)   Melting: ___________ state  __________
state.
melting
solid
liquid
liquid
solid

3. Explanation using KPT absorb energy vibrate overcome
When a solid is heated, the solid particles will ________ the
heat and gain ________ to ___________ more vigorously.
When enough heat is applied, the solid particles vibrates so
vigorously that they are able to ___________
the_______________________ holding the solid particles.
When this happen, the solid has turned into a _________;
________ has taken place.
energy
vibrate
overcome
forces of attraction
liquid
melting

4. Reading a Melting Curve
Note: This curve is only true for a pure compound
An experiment can be carried out and the result of the melting can be plotted as shown:
Temperature (ºC)
Melting starts
Temperature remains constant
Melting completes
Time from start (min)
Melting point (69°C)
SOLID
SOLID + LIQUID
LIQUID A B C D

5. Reading the melting curve
Graph shows how temperature of substance changes with time during
melting when it is heated steadily.
1. AB the substance is completely ______________.
2. Point B - ____________ begins at _________.
( The first drop of ________ appears).
3. BC ________ continues to take place. The substance
exists as a ________ of _____ and __________.
4. Point C – The last drop of _________ is formed.
5. CD – The substance is completely __________
( ) 
solid
melting
690C
liquid
melting
mixture
solid
liquid
liquid
liquid
molten

6. Think……
Why does the temperature remain constant between B and C even though heat is continuously supplied?
Ans: The heat is used to overcome the forces of attraction holding the solid particles instead of causing the temperature to rise.

7. Boiling
To explain the movement of particles in the process of _____________.
Boiling
 (a)   Melting: ___________ state  __________
state.
boiling
liquid
gaseous
gaseous
liquid

8. Explanation using KPT absorb energy vibrate overcome
When a liquid is heated, the liquid particles will ________ the
heat and gain ________ to ___________ more vigorously.
When enough heat is applied, the liquid particles vibrates so
vigorously that they are able to ___________
the_______________________ holding the liquid particles.
When this happen, the liquid has turned into a _________;
________ has taken place.
energy
vibrate
overcome
forces of attraction
gas
boiling

9. Reading a Boiling Curve
Note: This curve is only true for a pure compound
An experiment can be carried out and the result of the melting can be plotted as shown:
temperature (ºC)
time from start (min) X Y
74ºC W

10. Reading the boiling curve
Graph shows how temperature of substance changes with time during
melting when it is heated steadily.
1. WX the substance is completely ______________.
2. Point X - ____________ begins at _________.
( The first drop of ________ appears).
3. XY ________ continues to take place. The substance
exists as a ________ of _____ and __________.
4. Point Y – The last drop of ________change into
_________ state.
5. Beyond Y – The substance is completely __________
liquid
boiling
740C
gas
boiling
mixture
gas
liquid
liquid
gaseous
gaseous

11. Exercise: Combination of melting & boiling curve
Time from start / min
Tempt / 0C 40 60
120
completely gas
Mixture of liquid & gas
boiling point, 120oC
Mixture of solid & liquid
completely liquid
completely solid
melting point, 60oC