Changing states – ExtendCC1a.4Name Class Date

1 Cut the cards out and stick them in suitable positions on the grid below.

States of matterSolid Liquid Gas

2 Describe the differences in the arrangements and movement of particles in solids, liquids and gases.

Particles can movearound each other

Particles can only vibrateabout fixed positions

Particles are regularlyarranged

Particles are randomlyarranged

Particles arefar apart

Particles are randomlyarranged

Particles can move quicklyin all directions

Particles areclose together

Particles areclose together

Particle theory and states of matter – Homework 1 CC1a.5

Name Class Date

1 Name the state of matter in which the particles:

a are close together and randomly arranged.

b are regularly arranged.

c have no attractive forces between them.

2 Describe what happens to the arrangement and movement of particles when a substance boils.

3 Explain why changes of state are physical changes.

4 The diagram shows the cooling curve for substance X.

Add the labels a, b, c or d to the graph to show:

a where the substance is freezing

b the melting point of the substance

c where the substance is in the liquid state and cooling down

d where the mean energy of the particles is highest.

5 Butane is a fuel. Its melting point is −140 °C and its boiling point is −1 °C.

Predict the state of butane at −150 °C and at 25 °C.

6 Bromine is in its liquid state at 25 °C. Explain what this tells you about its melting point and boiling point.

Particle theory and states of matter – Homework 2 CC1a.6

1 a Name the three states of matter.

b Name the physical change that occurs between each state of matter, and describe the changes that occur.

c Name the state of a substance in which the mean energy of its particles is generally lowest.

2 Describe the arrangements and movement of particles of:

a water in a swimming pool

b water in an ice cube

c the air around you.

3 Explain, in terms of attractive forces between particles, why:

a energy must be transferred from the surroundings to the particles during boiling

b energy is transferred to the surroundings from the particles during freezing.

4 The table shows some melting points and boiling points.

Substance Melting point (°C) Boiling point (°C)

ethanol −114 78

ammonia −78 −33

fluorine −220 −188

mercury −39 357

a Copy the table below, and complete it to show the state of each substance at the temperature shown.

Temperature (°C) ethanol ammonia fluorine mercury

215

0

−215

b Ethanol and mercury are both used in making thermometers. Scientists use ‘ultra-low’ freezers to store heat-sensitive substances at −40 °C to −85 °C. Explain which type of thermometer, ethanol or mercury, would be most suitable for use in these freezers.

5 Some students did an experiment using a substance with a melting point of 70 °C. They heated some of the substance in a boiling tube to 85 °C, and then allowed it to cool. They recorded its temperature every minute until it reached 55 °C.

a Sketch a cooling curve for this experiment.

b On your diagram, mark the starting and finishing temperatures, and also the melting point.

c Identify the parts of the curve that show the substance cooling in the solid state.

Extra challengeFreeze-drying is used to prepare dehydrated foods such as instant coffee, pot snacks and powdered soup mixes. The food is cooled to between −50 °C and −80 °C, and then exposed to a very low air pressure. Under these conditions, any water in the food sublimes.

6 Explain, in terms of the arrangement and movement of water particles, the attractive forces between them and energy transfers, why:

a the food is first cooled down

b water in the food sublimes

c some heating is needed for sublimation to continue.

Progression CheckCC1aName Class Date

Progression questionsAnswer these questions.

1 What are particles like in substances in the solid, liquid and gas states?

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2 What changes happen to particles during the different changes of state?

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3 How do you decide what state a substance will be in at a given temperature?

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Now circle the faces in the ‘Start’ row in the table showing how confident you are of your answers.

Question 1 2 3

Start

AssessmentUsing a different colour, correct or add to your answers above. You may need to use the back of this sheet or another piece of paper. Then circle the faces in the ‘Check’ row in the table.

Question 1 2 3

Check

FeedbackWhat will you do next? Tick one box.

strengthen my learning strengthen then extend extend

Note down any specific areas you need to improve.

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ActionYou may now be given another activity. After this, note down any remaining areas you need to improve and how you will try to improve in these areas.

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