Chapter 3: States of Matter

By the end of this chapter, you will be able to:

1. understand the meaning of matter.
2. understand that atoms are the building blocks from which all matter is made; concentration appreciate that the states of matter have different properties.
3. apply the particle theory to explain diffusion and Brownian motion and their applications.
4. understand how the particle theory of matter explains the properties of solids, liquids and gases, changes of state and diffusion.

Keywords

• condensation
• diffusion
• evaporation
• gas
• liquid
• matter
• melting
• particle theory of matter
• plasma

3.1: Introduction

Nearly every substance in the world exists either as plasma can classify any substance. The difference of the substances in states is observed in the property differences. All these substances are actually pieces of matter. Recall that: in their Matter is anything that has mass and occupies space (volume).

In this chapter, you will learn more about matter and use the knowledge of the arrangement and motion of particles to explain the properties of solids, liquids, gases and plasma.

3.2: States of Matter

Activity 3.1 Identifying the states of matter Solic

Figure 3.1: States of matter In a tha Th giv int

Questions

1. Observe the above diagrams carefully and state the arrangement of particles in each of them.

2. Suggest a state of matter that each diagram represents. Give 3 examples on each state.

A single substance might exist in more than one of the three states, depending on the temperature and pressure. For example, water exists as a solid (ice), a liquid (water) and a gas (steam).

Currently, there are four states of matter in the scientific world! These few states are natural and include solid, liquid, gas, and plasma.

3.3: Properties of States of Matter

Solids

In a solid, particles are so tightly packed together that they do not move much. A stone (a solid substance)

Figure 3.2: Solid state of matter

Solids, therefore, have a high density because the particles making up the solid are tightly packed together.

The particles have small vibration, and they are fixed in their position. Because of this, particles in a solid have very low kinetic energy. Solids have a definite shape, as well as mass and volume.

Liquids

In a liquid, the particles making up the liquid are more loosely packed than in a solid.

The liquid particles are therefore more able to flow around each other, giving the liquid an indefinite shape. Therefore, the liquid will fit itself into the shape of its container.

Figure 3.3: Liquid state of matter

Much like solids, liquids (most of which have a lower density than solids) are also difficult to compress.

Gases

The particles of a gas are much farther apart than the particles in a liquid.

If a gas has a smell and colour, you will often be able to detect it before you can see it.

Figure 3.4: Arrangement of particles in a gaseous state

The particles that make up a gas have a great deal of space between them and have high kinetic energy.

The gas particles are in motion far more than the particles that make up a solid or liquids.

A gas has no definite shape or volume. If not confined, the particles of a gas will spread out indefinitely; if confined, the gas will expand to fill its container. When a gas is put under pressure by reducing the volume of the container, the space between particles is reduced. Therefore, a gas is easy to compress.

Plasma

Plasma occurs at extremely high temperatures. Plasma is not a common state of matter here on Earth, but it may be the most common state of matter in the universe.

Plasma is a state of matter that is often thought of as a subset of gases, but the two states behave very differently.

Like gases, plasmas have no fixed shape or volume, and are less dense than solids or liquids. But unlike ordinary gases, plasmas are made up of atoms in which some or all of the electrons have been stripped away and positively charged nuclei, called ions, roam freely.

Gas is made of neutral molecules and atoms while Plasma is a charged Plasma makes up the Sun and stars, and it is the most common state of matter in the universe as a whole. The other forms include gases in air during lightning.

You already know about the three states of matter called solids, liquids and gases. Plasma is the fourth state of matter and it is a very hot gas that has a lot more energy than the other three states of matter.

3.4: Changing States of Matter

What is a change in the physical state of matter?

Activity 3.2 Studying change of state of matter

Key Question: Can one state of matter change into another

What you need state?

A 500 ml beaker or a round bottomed flask (or a conical flask), a heat source (Bunsen burner or spirit candle), two (or three) cubes of ice/candle wax and a ring or tripod stand.

What to do

In groups:

a) Put the ice cubes inside the round bottomed flask.

b) Place the round bottomed flask containing the ice onto the stand (ring or tripod).

c) Heat the ice in the flask with your Bunsen burner (or spirit candle) by placing the heat source below the flask.

d) Continue heating till there is no more water in the flask.

e) Observe the changes (of the ice cubes or wax) that take place!

f) Record the changes that took place in your experiment.

g) Compare what you found out with what the rest of the other groups discovered. h) Present your findings to the rest of the class.

Cause of change of state

Adding or removing heat energy from matter causes a physical change as matter changes from one state to another.

For example, adding thermal energy (heat) to liquid water causes it to become steam or vapour (a gas).

And removing heat energy from liquid water causes it to become ice (a solid). Physical changes can also be caused by motion and pressure.

Activity 3.3 Knowing the process of change of state of matter

In groups, identify and explain each of the changes of state of matter indicated by letters a, b, c, d, e and f.

Advantages of change of state

The most common advantage is a biological process that occurs in human beings. This is sweating. Sweating is the release of a salt-based fluid from your body.

Sweating keeps US cool and comfortable and prevents the body from overheating in hot environments or during exercise.

As body temperature increases, sweat glands release sweat in order ase the temperature.

Sweat (liquid) leaves your skin through pores and evaporates (becomes gas) when it hits the outside air. As the sweat evaporates off your body, you cool down.

Sweating can also occur during sickness, since the body is burning energy to fight disease. Similarly, we may also sweat when encountering stressful situations or experiencing strong emotions: one of the reasons why you may feel ‘hot and bothered when upset or angry.

Assignment 3.1 Analysing the importance of change of state of matter

In groups:

a) Discuss how ice cubes are got from water.

b) Justify what you think would happen if the ice cubes are heated. Thus, explain the scientific phenomenon that explains this process.

c) From your understanding, why do you think heat is always taken in during melting and boiling and given out on condensation and freezing?

d) Make a report on your findings and then discuss it with the whole class.

3.5: The Particle/Kinetic Theory of Matter and Forces between Particles

According to the kinetic (particle) theory of matter, all matter consists of many, very small particles which are constantly moving.

The degree to which the particles move is determined by the amount of energy they have and their relationship to other particles.

Recall that these particles might be atoms, molecules or ions.

The particle theory helps us to explain the properties and behaviour of materials. It provides a model which enables us to visualise what is happening on a very small scale inside those materials

According to the Particle theory of matter:

Figure 3.6: liquid Arrangement of particles in matter gas

The model (the particle theory of matter) can be used to help explain:

the properties of matter.

what happens during physical changes such as melting, boiling and evaporating.

3.6: Evidence for Existence of Particles in States of Matter

Everything around us is made up of tiny pieces or particles. The particles which make up matter are atoms or molecules. Our body, chair, table, book etc. are all made up of particles.

Brownian motion

Brownian motion is the random motion of particles suspended in a fluid (a liquid or a gas) resulting from their collision with the fast-moving molecules in the fluid.

Activity 3.4 Investigating Brownian motion

What you need A smoke cell, light source, a lens, smoke source, pipette.

What to do

a) Fill the cell with smoke using a dropping pipette and cover it with a glass cover-slip.

b) Target the source of light through the smoke cell.

c) Observing from the opposite side, using a lens, look through the smoke cell.

Question

In groups, write short notes on what is observed.

3.7: Diffusion

Assignment 3.2 Understanding diffusion

In groups, brainstorm:

a) Why when curry powder is put in food, it can be smelt in all parts of the home.

Activity 3.5 Investigating diffusion in liquids

What you need

A 250 ml beaker, ink for a fountain pen, a dropper and a one- litre bottle filled with clean water.

What to do

While in pairs:

a) Pour into the beaker about 200 ml of water.

b) Draw the ink into the dropper.

c) Carefully, push the dropper to the bottom “corner” of the beaker with water and introduce the ink without disturbing the water.

d) Carefully, remove the dropper from the beaker

e) Observe what happens to the water in the beaker and record your observation.

f) Explain what has happened to the water.

g) Prepare a report and present it to the rest of the class.

From the deductions made in the activities above, the movement of the colours from one region to another is what we call diffusion.

Therefore, diffusion is the movement of a substance from an area of high concentration to an area of low concentration.

Diffusion happens in liquids and gases because their particles move randomly from place to place.

Activity 3.6 Discussing diffusion and Brown motion

1. In pairs, discuss where diffusion is experienced in daily life.
2. 2What are signicant differences between diffusion and Brownian motion? Present the information acquired to the class.

What causes diffusion?

In gases and liquids, particles move randomly from place to place. The particles collide with each other or with their container. This makes them change direction. Eventually, the particles are spread through the whole container. Diffusion happens on its own, without stirring, shaking or slight movement.

Why is diffusion useful?

In living things, substances move in and out of cells by diffusion.

For example:

1. Respiration produces waste carbon dioxide, causing the amount of carbon dioxide to increase in the cell. Eventually, the carbon dioxide concentration in the cell is higher than that in the surrounding blood. The carbon dioxide then diffuses out through the cell membrane and into the blood.
2. Water diffuses into plants through their root hair cells. The water moves from an area of high concentration (in the soil) to an area of lower concentration (in the root hair cell). This is because root hair cells are partially permeable. The diffusion of water like this, is called osmosis.

Diffusion in daily life

Being a universal physical phenomenon, diffusion happens all over daily life. Here are a few notable examples:

a) Food colouring. b) The scent of perfume. c) Carbon dioxide gas in soda bottles. d) Diffusion in the human body e.g. how oxygen enters the blood stream.

Assignment 3.3 Explain how diffusion applies in the above mentioned situations.

Activity 3.7 Investigating the relationship between temperature and diffusion

Key Question: What is the meaning of diffusion?

What you need

A source of heat, two (02) litres of clean water, 100 mls of food colour, a dropper, cotton wool (or a roll of toilet paper), one 1000 ml beaker, three (03) 250 ml beakers, a thermometer a 250 ml measuring cylinder and a stop clock

The beakers should be of transparent glass.

What to do

In groups:

1. Pour about 750 ml of clean water into the 1000 ml beaker.
2. Heat the water in the 1000 ml beaker to boiling point and keep it boiling.
3. Pour 200 mls of water into one 250 ml beaker.
4. Measure and record the temperature of the water in the beaker.
5. Using a dropper, add a single drop of colour to the water’s edge in the beaker and start timing the moment the drop hits the water.
6. Stop timing as soon as the colour first reaches the opposite edge of the beaker.
7. Note and record the time taken for the drop to reach the opposite edge of the beaker.
8. Get the second beaker and wrap it well with cotton wool (or tissue). This is called lagging the beaker.
9. Get the third beaker. Into this beaker, pour some hot water and then mix it with cool water till you get the temperature of the mixture to be 30°C.
10. Pour 250 ml of this water into the lagged beaker.
11. Add a single drop of food colour to the water’s edge in the container and start timing the moment the drop hits the water.
12. Stop timing as soon as the colour first reaches the opposite edge of the container and pour out the water. m)
13. Record the time measured.
14. Repeat from step j) up to step m) for the temperatures 40°C, 50°C, 60°C, 70°C and 80°C. n) 0)
15. record your results in a table as below:

Table of results

Questions

1. States of Matter What have you noticed about the times you have measured?
2. Plot a graph of Temperature in degrees Centigrade versus Time in seconds.
3. What is the relationship between temperature and the rate of diffusion?
4. As a group, write a report and present it to the rest of the class.

The rate of diffusion is affected by a number of factors:

a) Temperature.

b) Concentration.

C) The surface area of the exchange surface.

d) The size of the particles.

Assignment 3.4

Explain how each of these factors affects the rate of diffusion.

You can ask our super AI Physics teacher below questions of Physics s1-s4 and get answers