CHANGEOF STATE STATES OF MATTER There are three states, or phases, of matter. They are: Solid Liquid Gas When a substance changes from one state, or phase, of matter to another we say that it has undergone a change of state. MELTING The change of state from solid to liquid state is called melting. The temperature at which the solid states of the substance changes into the liquid states of the substance is called its melting point. The temperature remains constant until the entire amount solid is converted into liquid state VAPORISATION The change of state from liquid to vapour is called vaporisation. The liquid and vapour states of the substance coexist in thermal equilibrium during the change of state from liquid to vapour. The temperature at which the liquid states of the substance change to its vapour state is called its boiling point. CONDENSATION The process of changing gas (or vapour) to a liquid by cooling is called condensation Condensation is the reverse of boiling (or vaporisation). FREEZING The process f changing a liquid into a solid by cooling is called freezing Freezing is reverse of melting Freezing means solidification. SUBLIMATION AND DESPOSITION The process of changing of solid directly into vapour (or gas) is called sublimation. The process of changing of vapour (or gas) directly into solid is called sublimation and desposition. EFFECT OF PRESSURE ON MELTING POINT Under normal atmospheric pressure, ice melts at 0 °C. However, this can change if the air pressure changes. When the two ice cubes are pressed together, the melting point is lowered. The ice melts since its temperature (0 °C) is above the new melting point. When the ice cubes are released, the ice freezes again at 0 °C joining the two ice cubes together.

1. PRESENTED BY:-
SIMRAN KHIRBAT
IX A

3. There are three states, or phases, of
matter.
They are:
Solid
Liquid
Gas
When a substance changes from one state, or phase, of matter to
another we say that it has undergone a change of state.

4. CHANGE OF STATE

5. MELTING
The change of state from solid to liquid state is
called melting.
The temperature at which the solid states of the
substance changes into the liquid states of the
substance is called its melting point.
The temperature remains constant until the
entire amount solid is converted into liquid
state

6. VAPORISATION
The change of state from liquid to vapour is
called vaporisation.
The liquid and vapour states of the substance
coexist in thermal equilibrium during the change
of state from liquid to vapour.
The temperature at which the liquid states of
the substance change to its vapour state is
called its boiling point.

7. CONDENSATION
The process of changing gas (or
vapour) to a liquid by cooling is
called condensation
Condensation is the reverse of
boiling (or vaporisation).

8. FREEZING
The process f changing a liquid into a
solid by cooling is called freezing
Freezing is reverse of melting
Freezing means solidification.

9. The process of changing of solid directly
into vapour (or gas) is called sublimation.
The process of changing of vapour (or gas)
directly into solid is called sublimation and
desposition.

10. EFFECT OF PRESSURE ON
MELTING POINT

11. EFFECT OF PRESSURE ON
MELTING POINT
Under normal atmospheric pressure, ice melts at 0 °C.
However, this can change if the air pressure changes.
When the two ice cubes are pressed together, the melting point
is lowered.
The ice melts since its temperature (0 °C) is above the new
melting point.
 When the ice cubes are released, the ice freezes again at 0 °C
joining the two ice cubes together.