1. STATES OF MATTER LEARNING OUTCOMES Chapter 1
State evidence in support of the
particulate nature of matter
Explain the differences between the three
states of matter in terms of the arrangement
of particles

2. STATES OF MATTER States of Matter
Chapter 1
STATES OF MATTER
States of Matter
Matter can exist in 3 states: solid, liquid and gas.
For example, water can exist as:
ice (solid state),
water (liquid state) and
steam or water vapour (gaseous state).

3. STATES OF MATTER States of Matter
Chapter 1
STATES OF MATTER
States of Matter
The state in which a substance exists depends mainly on its temperature and pressure.
For example, iron is a solid at room temperature and pressure; but at around 1500 oC, it becomes a liquid.
Similarly, oxygen is a gas at room temperature and pressure, but at –183 oC, it is a liquid.

4. STATES OF MATTER Diffusion Chapter 1
Diffusion is the spontaneous movement of particles of a substance from a region of higher concentration to a region of lower concentration.
Diffusion occurs in all states of matter.
For solids, diffusion can be shown by placing a block of gold and a block of lead together. Some gold atoms will be found in the lead block and some lead atoms will be found in the gold block after a few years.

5. STATES OF MATTER Diffusion Chapter 1
For liquids, diffusion can be shown by placing a drop of ink or a crystal of purple potassium manganate(Vll) into a beaker of water.
After some time, a uniform purple colour is seen throughout the beaker.

6. STATES OF MATTER Diffusion Chapter 1
For gases, diffusion can be shown by setting up the apparatus shown below.
Soak a piece of swab with concentrated hydrochloric acid and insert it into one end of the glass tube.
2. Soak another piece of cotton swab with concentrated ammonia solution and insert it into the other end of the glass tube.
3. Seal both ends of the glass tube with rubber bungs and leave the tube horizontal.
4. After a few minutes, a white disc of ammonium chloride is formed.

7. The Three States of Matter
Chapter 3
The Three States of Matter
Rate of diffusion
The speed of diffusion is fastest in gases followed by liquids and very slowly in solids.
The rate of diffusion increases with temperature.
At higher temperatures, the particles have higher kinetic energy and hence move faster and diffuse at a faster rate.
At O oC
At 2O oC

8. The Three States of Matter
Chapter 3
The Three States of Matter
Rate of diffusion
The rate of diffusion also depends on the relative molecular mass of the particles.
Heavier particles will diffuse at a slower rate than lighter particles.
The rate of diffusion of a gas is inversely proportional to the square root of its relative molecular mass.

9. STATES OF MATTER Osmosis
Chapter 1
STATES OF MATTER
Osmosis
Osmosis is the movement of water molecules from a region of higher water concentration to a region of lower water concentration through a partially permeable membrane.
It is a special type of diffusion carried out by plants to obtain water and mineral salts from the soil.

10. Differences between solids, liquids and gases
Chapter 1
STATES OF MATTER
Differences between solids, liquids and gases
A solid has a fixed shape and a fixed volume. A solid cannot be compressed.
A liquid has a fixed volume but no fixed shape. A liquid cannot be compressed.
A gas has neither fixed shape nor volume. A gas can be easily compressed.

11. Differences in properties
Chapter 1
STATES OF MATTER
Differences in properties
Solid
Liquid
Gas
Particles are packed closely together in an orderly pattern.
Particles are close together, but not tightly packed.
Particles are very far apart.
Liquid particles can vibrate and move freely throughout the liquid.
Gas particles can vibrate and move very freely and randomly in all directions.
Solid particles can only vibrate in fixed positions but cannot move away from each other.

12. STATES OF MATTER The Particle Theory Chapter 1
According to this theory, the particles in matter are in a state of constant motion due to their kinetic energy.
Gas particles of a substance have more kinetic energy than liquid particles, while liquid particles have more kinetic energy than solid particles.
Hence, gas particles can move much more freely and quickly than liquid particles, which in turn, can move more freely than solid particles.
Matter can be converted from one state to another by changing the amount of energy of the particles. If a matter gains heat energy, the particles will move faster and further apart, thus changing from a more orderly state to a more disorderly state.
Conversely, if heat energy is removed from a matter, the particles will slow down and move closer together, thus resulting in a more orderly state.

13. STATES OF MATTER Melting
Chapter 1
STATES OF MATTER
Melting
Melting is the change from a solid to a liquid.
The temperature at which a solid melts is called its melting point.
A pure substance has a fixed melting point.
E.g. The melting point of ice is 0 oC.
melting
Solid
Liquid

14. STATES OF MATTER Melting point graph Chapter 1
During melting, heat energy is absorbed by the solid.
The temperature remains constant during melting because the heat absorbed is used to overcome the forces of attraction between the solid particles instead of using it to raise its temperature.
A melting point graph can be plotted for a solid which undergoes heating, and its melting point can be determined from the graph.
Temperature/oC
Liquid state
Melting point 
solid + liquid
solid state
Melting point graph

15. STATES OF MATTER Freezing Chapter 1
Freezing is the change from a liquid to a solid. It is the reverse of melting.
The temperature at which a liquid freezes is called its freezing point.
For most pure substances, the freezing point is the same as the melting point. E.g. The melting point of ice and the freezing point of water are both 0 oC.
freezing
Solid
Liquid

16. STATES OF MATTER Freezing point graph Chapter 1
During freezing, heat energy is released (given out) by the liquid particles as they slow down and move closer together to take up the orderly positions of a solid.
The temperature remains constant during freezing because the heat given out compensates for the loss of heat to the surroundings.
A freezing point graph (or cooling curve) can be plotted, and the freezing point of the liquid can be determined from the graph.
Temperature/oC
Liquid state
Freezing point 
solid + liquid
solid state
Freezing point graph

17. STATES OF MATTER Boiling Chapter 1
Boiling is the change from a liquid to a gas or vapour.
The temperature at which a liquid boils is called its boiling point.
A pure substance has a fixed boiling point.
E.g. The boiling point of water is 100 oC under normal atmospheric pressure.
boiling
Liquid
Gas

18. STATES OF MATTER Boiling point graph Chapter 1
During boiling, heat energy is absorbed by the liquid particles to change into a gas.
The heat energy absorbed is used to overcome the forces of attraction between the liquid particles and to increase their kinetic energy until they have sufficient energy to escape from the liquid.
The temperature of a liquid remains constant during boiling as the heat energy absorbed is used to increase the kinetic energy of the particles and not to raise its temperature.
Gaseous state
Boiling point 
Liquid + gas
Liquid state
Boiling point graph

19. Evaporation STATES OF MATTER Chapter 1
Evaporation is the change from liquid into gas without boiling E.g. A drop of ethanol or perfume evaporates at room temperature.
Evaporation occurs below its boiling point.
Evaporation only takes place at the surface of a liquid.
Evaporation takes place slowly.
Evaporation produces a cooling effect because heat energy is absorbed from the surroundings.

20. Condensation STATES OF MATTER
Chapter 1
STATES OF MATTER
Condensation
Condensation is the change from a gas to a liquid. It is the reverse of boiling.
Heat energy is released (given out) during condensation as the gas particles slow down and move closer together to become a liquid.
The temperature of a substance remains constant during condensation since the heat given out compensates for the loss of heat to the surroundings.

21. STATES OF MATTER Sublimation Chapter 1
Sublimation is the change from a solid directly into a gas without melting.
For example, iodine crystals sublime into purple iodine vapour when heated.
Iodine vapour
Sublimation
Solid iodine
Gas
Solid
Other examples of solids which sublime are dry ice, ammonium chloride and naphthalene.

22. STATES OF MATTER Summary Chapter 1 Liquid Solid Gas Melting
(energy absorbed)
Liquid
Solid
Freezing
(energy released)
(energy released)
Condensation
(energy absorbed)
Sublimation
Boiling / Evaporation
(energy absorbed)
Gas

23. STATES OF MATTER Quick check 1 Chapter 1
State whether heat energy is absorbed or released in each of the following processes: (a) melting, (b) boiling, (c) freezing, (d) condensation
State whether the speed of the particles increases or decreases during: (a) melting, (b) condensation, (c) boiling, (d) freezing
The information below gives the melting points and boiling points of four substances: Substance Melting point (oC) Boiling point (oC)
W −123 − X − Y Z
(a) For each substance, state whether it is a solid, a liquid or a gas at room temperature and pressure. (b) In which substance are the particles furthest apart at −60 oC?
Solution

24. Solution to Quick check 1
Chapter 1
STATES OF MATTER
Solution to Quick check 1
(a) melting – heat absorbed, (b) boiling – heat absorbed, (c) freezing – heat released, (d) condensation – heat released
2. (a) melting – increases, (b) condensation – decreases, (c) boiling – increases, (d) freezing – decreases
Substance Melting point (oC) Boiling point (oC)
W −123 − X − Y Z
(a) W: gas, X: liquid, Y: solid, Z: liquid
(b) W
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