1.1 - 1.7 The three states
1.1 Introducing the states
Matter can exist in one of three fundamental states: Solid, Liquid or Gas
Here we consider the way in which these three states behave
We see how matter can be converted from one state into another and we introduce the terms used for these changes.
Evaporation, condensation, melting, freezing , sublimation and deposition.
It is important to be able to recall and explain the properties and behaviour of solids liquids and gases.
We also look at the way in which some substances dissolve in others and consider the terms :
1.1 - 1.2 Three fundamental states of matter
1.1 understand the three states of matter in terms of the arrangement, movement and energy of the particles
1.2 understand the interconversions between the three states of matter in terms of:
- the names of the interconversions
- the names of the interconversions
- how they are achieved
- the changes in arrangement, movement and energy of the particles.
1.2 Activity 1: Properties of the states
All matter is made up of particles. In solids, liquids and gases, the particles might be ions, molecules or atoms.
Watch the first 70 seconds of the video. Use your own words to describe the motion of the particles, the behaviour, shape and volume of a material when it is a :
- In a solid the particles vibrate but the solid remains in a fixed shape. The solid has a fixed density and cannot be compressed
- In a liquid the particles have enough energy to move freely and the liquid can therefore flow. A liquid will take up the shape of the container in which it is placed. The liquid cannot easily be compressed.
- In a gas the particles are widely spaced and move freely. The gas will fill the container in which it is placed. Gases can be compressed.
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1.2 Activity 2: Name the changes
Heating a material will give energy to its particles and cause them to move more rapidly. Cooling does the opposite. Heating or cooling can therefore cause a material to undergo a change of state.
With three principal states of matter there are six possible changes depending on whether we are heating or cooling the substances. These are shown in the table below.
1.2 Activity 3. Complete the matching exercise below
1.3 Activity 4. A particular problem
1.3 understand how the results of experiments involving the dilution of coloured solutions and diffusion of gases can be explained
Particle theory states that all matter consists of many, very small particles which are constantly moving or in a continual state of motion. This theory helps us to explain how food colouring dissolves in water so that the colour spreads evenly throughout.
Diffusion happens in liquids and gases because their particles move randomly from place to place. Diffusion is an important process for living things; it is how substances move in and out of cells.
1.4 Activity 5 : Defining diffusion, diluting and dissolving
Gases can diffuse into each other . This is because the particles in a gas are in a state of constant random motion.
Liquids can diffuse into other liquids. When the two liquids mix well in each other they are said to be soluble.The diffusing of one liquid ( the solute) into another ( the solvent) results in the dilution of the solute by the solvent.
The food colouring video here shows dilution in action.
Dilution Open or Close
Dilution is the process of decreasing the concentration of a solute in a solution, usually simply by mixing with more solvent like adding more water to a solution.
Diffusion Open or Close
Diffusion is the movement of a substance from an area of high concentration to an area of low concentration.
Dissolving Open or Close
Solids, liquids, and gases can all dissolve. Dissolving depends on the molecules of the substance doing the dissolving, called the solvent, and the molecules of the substance being dissolved, called the solute. Dissolving is the process in which these molecules interact and attract each other to form a solution.
Watch both the video and the animation carefully.
In your own words:
- Describe what happens.
- Try to explain what happens
- Explain why the colour spreads faster in the hot beaker
Use the each of the following words at least once:
1.4 - 1.7 What's the best solution?
1.6C understand how to plot and interpret solubility curves
1.7C practical: investigate the solubility of a solid in water at a specific temperature
Watch the video carefully and write down your answers to the questions before revealing them by clicking on each questions in turn.
1. Is solubility a physical or a chemical property ? Open or Close
The solublity of a substance is a physical property.
Other physical properties are :
- melting point
- boiling point
2. How does solubility of a solid change when temperature rises? Open or Close
The solublity of most solids increases as the temperature increases. This rule applies to most solids but is the opposite with gases. Gases become less soluble as the temperature increases.
3. What are the units for solubility? Open or Close
The solubility of a substance is often measured in grams per 100g water. These are the units used in the video shown.
4. How does the solubility of copper sulfate compare with that of potassium sulfate? Open or Close
The solubility of copper sulfate is greater than that of potassium sulfate at all temperatures.
5. What is the solubility of potassium sulfate at 60 degrees C? Open or Close
The solubility of potassium sulfate at 60oC is 18g/100cm3
6. What is a saturated solution ? Open or Close
What is a saturated solution ?
- 7. What happens when a saturated solution is cooled? Open or Close