Topic review Using scientific language 1. You should be familiar with the words in the following list. condense solid boiling matter gas diffusion melting solidify particles substance liquid property compression mass freeze model evaporate volume density sublime a Choose at least 12 words from the list and draw a labelled diagram of an experiment that involves all the words you have chosen. b Below your diagram, outline the experiment using the words you have chosen and underline them.
Check your knowledge 1. Name the state of matter that has: a a definite volume but takes the shape of the containers b a definite shape and volume c no definite volume but fills the container completely 2. Match the property of matter in the box with the correct description below. a particles of one substance moving between particles of another substance b the distance between particles being increased c particles of a substance being forced closer together expansion diffusion compression vibration 3. For each of the following sentences, choose the word in brackets that makes the sentence correct. a If the temperature of a gas is increased, its (mass, volume, weight, particle size) also increases. b The particles of matter move slowest in a (solid, liquid, gas).
Apply your skills 1. Choose 10 objects in your classroom. a Make a list of the objects and write down at least one physical property of each. b Classify or group the 10 objects based on their physical properties. For each group, describe the property on which you based your classifications. 2. a For each of the following diagrams, decide which state of matter is represented. b The five beakers represent the contents at different times as a solid substance is heated. Arrange the beakers in the correct order to show what happens when the solid is heated until the liquid form evaporates. Write down the order you have decided on. 3. A beaker which is half-filled with water is sitting on a bench in your laboratory. Imagine that you are a particle in the water. A student is asked by the science teacher to use the beaker to show the evaporation of water and condensation of steam. Write an imaginary story called "A Day in the Life of a Water Particle" to describe what happens. 4. Explain why it is necessary to put "antifreeze" in the radiators of cars when travelling in very cold areas.
5. State whether energy is needed or released when: a ice melts b water freezes Challenge yourself 1. The table below shows the boiling points of various gases present in air. Gas Boiling point ( C) helium -268.9 neon -245.9 nitrogen -195.8 argon -185.7 oxygen -182.7 krypton -152.9 xenon -107.1 If the air can be liquified at about -200 C, list the gases which would not be liquid at this temperature. 2. You go on a bike ride on a hot summer s day. Consider the particles of air in the tyres. a Describe their movement (i) at the start of the ride (ii) at the end of the ride. b Explain why this has happened. 3. Why is salt sometimes spread on roads and airport runaways in winter in cold countries?
Answers Using scientific language Students should use scientific diagrams of equipment. A good example would be melting an ice cube in an evaporating basin over a Bunsen burner. Check your knowledge 1. a liquid b solid c gas 2. a diffusion b expansion c compression 3. a volume b solid Apply your skills 1. a Properties could include: state at room temperature; boiling point; melting point; hardness; whether shiny or dull; whether it can be bent. b Solids, liquids and gases is a good starting point. Other possibilities include flammable/non-flammable, metallic-looking/non-metallic-looking, etc. 2. a a:liquid; b:gas; c:liquid (with some evaporation, probably due to boiling); d:solid; e:solid (melting) b d, e, a, c, b 3. The story should include moving around with all the other water particles, flying out of the beaker at escape velocity, hitting the cool watchglass and meeting up with lots of other water particles. 4. Antifreeze lowers the freezing point of the radiator contents and keeps the cooling system functional. If the water did freeze it could split the radiator, as water expands on freezing. 5. a needed b released