Y7 Review

1: Explaining change of state

Concept 2 Melting and boiling points

Concept 3: Effects on melting and boiling points.

Concept 4 Factors that affect solubility

Complete homework topic 10: Forces and motion.

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To be marked in class on Monday 14th October.

9C1: Particles

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Y7 & Y8 Review

Concept 1: Explaining changes of state

Concept 2: Melting and boiling points

Concept 3: Effects on melting and boiling points

Concept 4: Factors that effect solubility

Answer the multiple choice questions about what you learned in years 7 & 8 about topic C2: Particles

On pages 31 - 32

Be prepared to tell me your score on each area:

1 finger 2 fingers 3 fingers

WHAT IS A PARTICLE?

• All substances are made up of particles.
• Particles are tiny, you cannot see them with the naked eye.
• In a pure substance, all of the particles are the same.
• Particles do not change when the state of matter changes – water particles in ice are the same as the ones in water and steam.

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HOW ARE PARTICLES ARRANGED IN SOLIDS?

The particles in a solid forms a regular shape with a fixed volume.

All of the particles are touching other particles.

The particles cannot move around, just vibrate around a fixed point.

The particles do not flow – they cannot move.

They cannot be compressed – there is not space to move into.

HOW ARE PARTICLES ARRANGED IN A LIQUID?

Particles are touching other particles around them.

The particles have a fixed volume. They always take the shape of their container.

The particles are able to move over each other – this is why liquids can flow.

Liquids cannot be compressed. There is no space between the particles for them to go into when put under pressure.

HOW ARE PARTICLES ARRANGED IN A GAS?

Gas particles move around freely and spread far away from each other.

As gas particles have a lot of space between them, more particles can be added to a space, so gases can be compressed.

Gases will take the shape and volume of their container – for example a balloon.

As gas particles are able to move around each other, they are able to flow.

Complete the tasks on pages 33 - 34

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 atoms or molecules in the gas or liquid. It iis named after the botanist Robert Brown.

Write a definition of Brownian motion into the space at the top of page 35

DIFFUSION

Diffusion is the net movement of particles molecules from a region of higher concentration to a region of lower concentration.

Complete the gap-fill about diffusion in the middle of page 35

WATER

What do we call the different states of matter for water?

SOLID

LIQUID

GAS

ICE

WATER

STEAM or

WATER VAPOUR

CHANGES OF STATE

Ice, water and steam are all made up of the same type of particles – they are arranged in different ways.

1. What is happening to it.
2. What is happening to the temperature of the ice as it sits on your hand?
3. What is happening to the amount of kinetic energy in the ice as it warms up?
4. What is happening to the strong forces of attraction between the molecules as the ice melts?
5. What do you think is needed for this to happen?
6. Where does this energy come from?
7. What does your hand feel like as this is happening?

Hold a cube of ice on your hand and discuss these questions with your partner:

CHANGES OF STATE �this is what we are going to investigate next lesson.

SUBLIMATION

The particles can change from one state to another. When they do this, the particles rearrange and behave differently.

Complete the tasks on pages 131 and 132

9C1: Particles

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Y7 & Y8 Review

Concept 1: Explaining changes of state

Concept 2: Melting and boiling points

Concept 3: Effects on melting and boiling points

Concept 4: Factors that effect solubility

Answer questions 1 and 2 on page 37.

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1. The particles gain energy from their surroundings and this energy overcomes the forces of attraction between the particles.
2. A) particles vibrate more, they gain kinetic energy

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Answer questions 1 and 2 on page 37.

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When you heat a substance the thermal energy you provide to heat it is absorbed by the substance itself.

What happens to this thermal energy?

The energy stored in the movement of the particles is called thermal energy.

Thermal energy from a hand is absorbed by the ice cube.

• The hand will feel cooler as thermal energy is transferred from it; it gets cooler
• The ice cube gains thermal energy, it becomes hotter, the ice cube starts to melt

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• When a solid stores more thermal energy, the vibrations of its particles increase.

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• When a liquid or gas stores more thermal energy, the particles speed increases.

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• The temperature of a substance is a measure of the movement of the particles.

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• Temperature is not the same as thermal energy. For example, a kettle full of boiling water stores more energy than a cup full of water at the same temperature.

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What happens during a change of state

Heating curves

1. On page 39, plot a graph of the results on page 38, choosing appropriate scales for the axes.
2. Make sure both axes are clearly labelled.
3. Label the temperature when the ice was melting. What do you notice about the shape of the graph at this point?
4. Draw a smooth curve of best fit.
5. Write a conclusion by filling in the gaps and answering questions 2 & 3 on pages 39 & 40.

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Complete tasks 1 and 2 on pages 41 & 42

Conclusion: Page 39

1. The sloped sections on these graphs represent one ____________ of matter and a changing t________________. The flat sections on these graphs represent a change of ____________ and a constant t____________.

2) Label the different states of matter and the change of state shown on your graph.

3. When a substances change state from a s…………… to a l…….……. or a l……..….. to g…….…., e………..….. is transferred from the s…….…….. to the p……..…………. in order to break the f………….. of a…….………….. between the particles. M…….… energy is needed to change the particles from a l…….………. to g…….. than a s…….……… to l…………..….

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state

emperature

state emperature

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Task 1

Complete tasks 1 (page 136), task 2 (137) and task s 3 & 4 (142 – 143)

Task 2

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1. Label the sections on the graph where the substance is a solid, liquid and a gas?
2. Label the change of states.
3. What is this substance i) melting point ii) boiling point?
4. Describe the way that the particles are arranged and behaving between i) P-Q, ii) R-S, iii) T-U
5. Why does the substance stop heating up at Q-R and S-T? (Mention where the energy has been transferred to and from)
6. How does the energy needed for melting compare to boiling?

The graph showing what would happen if you took a solid substance and heated it over time. When the temperature is measured, it goes up and up most of the time but at certain points it does not change.

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By answering these questions, we will think about what is happening at those points and what they can tell us.

Heating curve: melting ice

Here is some guidance on drawing best fit and scatter graphs:

1) Make sure you know what goes on the horizontal (x) axis and what goes on the vertical (y) axis. The input / independent variable goes on the horizontal axis.

2) Work out a scale for each axis. The scale must use more than half the axis. Find the biggest value to go on the scale and then choose a scale to fit. Each square must be worth the same value. It is best to do this in pencil.

3) Label each axis with the name and units. Do this in pen.

4) Plot the points using X’s (best in pencil).

5) If there is a clear pattern, draw a single best fit line. This can be curved or straight. It must go through or as close to the points as possible. There should be a similar number of points on each side of the line. Draw the line in pencil (with a ruler if you think it is)

Complete the graph and write complete the conclusion questions 1 - 3.

Cooling curves experiment

Safety:

• Safety glasses worn at all times
• Long hair tied back.
• Blazers removed.
• Do not touch the hot equipment

salol

Cooling curves

1. On page 44, plot a graph of your results and the secondary data on page 43, choosing appropriate scales for the axes.
2. Make sure both axes are clearly labelled.
3. Label the temperature at which the salol was freezing. What do you notice about the shape of the graph at this point?
4. Draw a smooth line of best fit (not necessarily a straight line).
5. The temperature should stay constant at 69.3°C while the stearic acid is melting, but often the temperature continues to go down slowly. Why might your experimental results not show a perfect horizontal line at 69.3°C?

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2. Label the temperature when the stearic acid was freezing. What do you notice about the shape of the graph at this point?
3. Draw a smooth curve of best fit.
4. The temperature should stay constant at 69.3°C while the stearic acid is melting, but often the temperature continues to go down slowly. Why might your experimental results not show a perfect horizontal line at 69.3°C?

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Cooling curve for salol

Heating curve for water

Conclusion: Page 39

1. The sloped sections on these graphs represent one ____________ of matter and a changing t________________. The flat sections on these graphs represent a change of ____________ and a constant t____________.

2) Label the different states of matter and the change of state shown on your graph.

3. When a substances change state from a s…………… to a l…….……. or a l……..….. to g…….…., e………..….. is transferred from the s…….…….. to the p……..…………. in order to break the f………….. of a…….………….. between the particles. M…….… energy is needed to change the particles from a l…….………. to g…….. than a s…….……… to l…………..….

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state

emperature

state emperature

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Task 1

Complete tasks 1 (page 136), task 2 (137) and task s 3 & 4 (142 – 143)

Task 2

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1. Label the sections on the graph where the substance is a solid, liquid and a gas?
2. Label the change of states.
3. What is this substance i) melting point ii) boiling point?
4. Describe the way that the particles are arranged and behaving between i) P-Q, ii) R-S, iii) T-U
5. Why does the substance stop heating up at Q-R and S-T? (Mention where the energy has been transferred to and from)
6. How does the energy needed for melting compare to boiling?

The graph showing what would happen if you took a solid substance and heated it over time. When the temperature is measured, it goes up and up most of the time but at certain points it does not change.

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By answering these questions, we will think about what is happening at those points and what they can tell us.

Answers to pages 45 - 47 on visualiser

9C2: Particles

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Y7 & Y8 Review

Concept 1: Explaining changes of state

Concept 2: Melting and boiling points

Concept 3: Effects on melting and boiling points

Concept 4: Factors that effect solubility

Melting and boiling points

Melting and boiling points

Answer all the questions on pages 49 – 51 – the melting point of lead is 327^oC

Chlorine forms diatomic atoms with the formula: Cl₂

Chlorine molecules in a solid

Chlorine molecules in a gas

There are forces of attraction between the atoms in the molecule and between the separate molecules in a substance

Copper molecules in a solid

Page 49

Who is right? Why?

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Who is wrong? Why?

Melting observations

Cooling observations

Predict the state of substances using melting and boiling points at a given temperature�

Worked example – element X

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• Element X has a melting point of -38.9 °C. Above this temperature element X is in the liquid state.
• Element X has a boiling point of 357°C. Above this temperature, element X is in the gas state.

357°C

-38.9 °C

What state is element X at:

1. -400^oC
2. -50^oC
3. 0^oC
4. today’s room temperature
5. 100^oC
6. 400^oC

Predict the state of substances using melting and boiling points at a given temperature�

Gold:

• has a melting point of 1065°C. Above this temperature it is in the liquid state.
• has a boiling point of 2710°C. Above this temperature, it is in the gas state.

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What state is gold at:

1. -400^oC
2. -50^oC
3. 0^oC
4. today’s room temperature
5. 100^oC
6. 400^oC

Predict the state of substances using melting and boiling points at a given temperature�

Oxygen:

• has a melting point of -218°C. Above this temperature it is in the liquid state.
• has a boiling point of -183°C. Above this temperature, it is in the gas state.

What state is oxygen at:

1. -400^oC
2. -50^oC
3. 0^oC
4. today’s room temperature
5. 100^oC
6. 400^oC

Sketch a thermometer like this in the back of your workbooks, ready to answer some YMCA questions.

Y

M

C

A

solid

1/6

Oxygen:

• has a melting point of -218°C.
• has a boiling point of -183°C.
• What state is it at -250^oC?

liquid

gas

can’t tell

Click again for answer

Y

M

C

A

solid

1/6

Oxygen:

• has a melting point of -218°C.
• has a boiling point of -183°C.
• What state is it at -250^oC?

liquid

gas

can’t tell

Click again for answer

Y

M

C

A

solid

1/6

Oxygen:

• has a melting point of -218°C.
• has a boiling point of -183°C.
• What state is it at -250^oC?

liquid

gas

can’t tell

Click again for answer

Y

M

C

A

solid

1/6

Oxygen:

• has a melting point of -218°C.
• has a boiling point of -183°C.
• What state is it at -194^oC?

liquid

gas

can’t tell

Click again for answer

Y

M

C

A

solid

1/6

Phosphorous:

• has a melting point of 44°C.
• has a boiling point of 281°C.
• What state is it at 100^oC?

liquid

gas

can’t tell

Click again for answer

Y

M

C

A

solid

1/6

Mercury:

• has a melting point of -39°C.
• has a boiling point of 357°C.
• What state is it at 100^oC?

liquid

gas

can’t tell

Click again for answer

Y

M

C

A

solid

1/6

Mercury:

• has a melting point of -39°C.
• has a boiling point of 357°C.
• What state is it at 400^oC?

liquid

gas

can’t tell

Click again for answer

Y

M

C

A

solid

1/6

Mercury:

• has a melting point of -39°C.
• has a boiling point of 357°C.
• What state is it at -38^oC?

liquid

gas

can’t tell

Click again for answer

States at room temperature- Me, we, you

Answer the questions on pages 53 & 54 and the first question on page 55

visualizer

Explaining melting points

Magnesium has a melting point of 650°C.

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Oxygen has a melting point of -218°C.

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Magnesium oxide has a melting point of 2852°

Answer the questions on pages 55 & 56

visualizer

9C2: Particles

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Y7 & Y8 Review

Concept 1: Explaining changes of state

Concept 2: Melting and boiling points

Concept 3: Effects on melting and boiling points

Concept 4: Factors that effect solubility

How can we use melting and boiling point to find out if a substance pure?

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Why (other than for flavour) do cooks boil pasta and vegetables in salted water?

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Why do the site team scatter salt on the paths and playground in bad weather?

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Pure Substances

• A pure substance has a fixed melting point and boiling point
• They will always melt or boil at exactly the same temperature.
• For example, the melting point of pure water is 0 °C and its boiling point is 100 °C.
• We are going to investigate what happens when you add an impurity – salt to water.
• Practical: Why do cooks add salt (sodium chloride) when cooking vegetables, for example green beans?
• Write a hypothesis on the lined pages at the back of your workbook and we’ll see who is right.

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Pure Substances

• We are going to investigate what happens when you add an impurity – salt to water.
• Practical: Why do cooks add salt (sodium chloride) when cooking vegetables, for example green beans?
• Write a hypothesis on the lined pages at the back of your workbook and we’ll see who is right.

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Wear goggles, tuck in ties, hair up!

• We need to measure the boiling points of three solutions containing different amounts of dissolved salt.
• You will only do one solution and other groups will test the other solutions.
• Follow the instructions on page 57 of your workbooks to determine the boiling point of your test solution.
• Share your results with the two groups near you who are doing the other concentrations.

How can we use melting and boiling point to find out if a substance pure?

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Why (other than for flavour) do cooks boil pasta and vegetables in salted water?

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Why do the site team scatter salt on the paths and playground in bad weather?

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last lesson you measured the boiling points of three solutions containing different amounts of dissolved salt.

Analysis

Complete your analysis by answering these questions on page 58.

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Look at your hypothesis – were you right?

Analysis

Thinking about

1. What is the effect on the boiling point of water of adding the amount of salt that cooks usually use?
2. Do you think that this would make a significant difference to the cooking time
3. How could you alter the set-up of your experiment to minimise human error and to therefore gain more accurate results?

Complete your analysis by answering these questions on page 58.

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Look at your hypothesis – were you right?

Results from experiment to test the effect of salt on the boiling point of water

• What conclusions can you draw from these experimental results
• As the x axis variable …… the y-axis variable …..
• Answer all the questions on page 153

0 5 10 15 20 25 30

g salt added to 150cm³ water

Boiling point (^oC)

Melting Point

Watch the demo to see how solder melts compared to tin and lead.

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Solder is made from the elements tin (melting point - 232 °C ) and copper (melting point - 1085 °C).

Prediction: Will the solder melting point be higher of lower than the two metals?

Recorded the observations of the demonstration and explain what you saw.

Solder has a lower melting point (180 °C/453 K) compared to that of its constituent elements tin (232 °C/ 505 K) and lead (327 °C/ 600 K).

9W1 start here

Boiling Point Elevation

• Adding salt to water increases the boiling point of water.
• Why does this help cook food more quickly?

Freezing Point Depression

• However, the OPPOSITE occurs when freezing impure water.

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• The freezing point of water decreases when salt is added.

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• Why are roads gritted�in snowy weather?

Answer task 1 on page 58

9C2: Particles

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Y7 & Y8 Review

Concept 1: Explaining changes of state

Concept 2: Melting and boiling points

Concept 3: Effects on melting and boiling points

Concept 4: Factors that affect solubility

Solubility curves

Complete the Year 7 review on page 59

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• The substance that dissolves is called a .
• The liquid it dissolves into is called the .
• The mixture of them together is called a .
• Substances that can dissolve are called .
• Substances that cannot dissolve are called .

Insoluble, solvent, solution, solute, soluble

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Solubility curves

• The substance that dissolves is called a solute.
• The liquid it dissolves into is called the solvent.
• The mixture of them together is called a solution.
• Substances that can dissolve are called soluble.
• Substances that cannot dissolve are called insoluble.

Solubility

• If a substance is soluble it will dissolve in a given amount of liquid (called the ‘solvent’).
• Different substances have different solubilities.

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• In general, solids become more soluble as the temperature increases. This is why sugar dissolves better in hot water than in cold water. The table shows three examples of the solubility (g of solute per 100 g water) of substances at different temperatures.

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Why do you think more solute can dissolve in hotter solutes?

Solubility curves�

• The solubility of a substance in water at different temperatures can be displayed using a solubility curve.

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• Solubility curves can be used to determine the mass of crystals formed when a solution is cooled.

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• Each solute has a different solubility at different temperatures and the change in solubility with temperature depends on the solute.

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The aim of this experiment is to construct a solubility curve for aluminium chloride . �

You are going to:

• Set up a hot water bath and an ice bath.
• Put 2.6 g of ammonium chloride into the boiling tube. Add a volume of freshly boiled water and warm it until the solid dissolves.
• Then, transfer the boiling tube to the ice bath and stir with the thermometer and note the temperature at which crystals first appear.
• You will each add a different amount of hot water and note the temperature at which crystals appear.

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Aim: to construct a solubility curve for aluminium chloride �

Safety: Wear eye protection.

Method:

• Collect your apparatus: Boiling tube
• 2 x 250ml beaker
• Weigh boat
• Spoon/Spatula
• Stirring thermometer (-10-110°C)
• 10ml measuring cylinder
• Pipette
• Boiling tube tongs

The aim of this experiment is to construct a solubility curve for aluminium chloride . �

Safety: Wear eye protection.

Method:

1. Set up a hot water bath and an ice bath. Put 2.6 g of ammonium chloride (Harmful if swallowed, eye irritant) into the boiling tube. Add 4 cm³ of freshly boiled water

2. Warm the boiling tube in the hot water bath until the solid dissolves.

3. Put the boiling tube in the ice bath and stir with the thermometer. Use tongs to hold it if necessary.

4. Note the temperature at which crystals first appear and record it in the table

5. Add another 1 cm³ water to the same test tube. Warm the solution again in your water bath, stirring until all the crystals dissolve.

6. Then repeat the cooling and note the new temperature at which crystals appear. Add more ice if you need to.

7. Repeat steps 5, 6 and 7 until a total of 9 cm3 water has been added.

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Solubility of ammonium chloride at different temperatures

Video

Aim: to construct a solubility curve for aluminium chloride �

Safety: Wear eye protection.

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1. Set up a hot water bath and an ice bath.
2. Measure out 2.6 g of ammonium chloride (Harmful if swallowed, eye irritant) into the boiling tube.
3. Use the pipette to add 4 cm3 of freshly boiled water GENTLY to the ammonium chloride.
4. Warm the boiling tube in the hot water bath until the solid dissolves.

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Aim: to construct a solubility curve for aluminium chloride �

Safety: Wear eye protection.

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5. Put the boiling tube in the ice bath and stir with the thermometer. Use tongs to hold it if necessary.
6. Watch carefully and note the temperature at which crystals first appear and record it in the table
7. Add another 1 cm3 water to the same test tube. Warm the solution again in your water bath, stirring until all the crystals dissolve.

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Aim: to construct a solubility curve for aluminium chloride �

Safety: Wear eye protection.

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8. Then repeat the cooling and note the new temperature at which crystals appear. Add more ice if you need to.
9. Repeat steps 5, 6 and 7 until a total of 9 cm3 water has been added.

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Choose your speed

take it easy with Mrs Spalding

OR

take the fast lane to finish your graph, the conclusions and questions on page 61, then the past paper questions on pages 63 – 68.

Page 60 - what are the dependent, independent and control variables in the experiment?

Page 61 - plot a graph of solubility (in grams per 100 g of water) against the temperature (temperature should be on the x-axis).

Graphing

Scale

Plot

Line of best fit

Axes

Title

Analysis of results

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What is the relationship between solubility?

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Almost always, start this. by using this sentence structure:

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As the (value on the x axis) increases the (value on the y-axis) ………

Additional questions

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1. What is meant by a saturated solution?
2. Explain why crystals formed in the tube
3. What mass of Ammonium Chloride would dissolve in 100 g of water at 50°C?
4. At what temperature would 40 g of Ammonium Chloride dissolve in 100 g of water?
5. What would be the mass of a saturated solution of Ammonium Chloride in 100 g of water at 35°C?

What’s weird about CO₂ and why is this a major problem?

p. 63

p. 64

Answer the PPQs on pages 64 - 67

p. 65

p. 66

p. 67

p.68