Year 8 Science Home Learning Pack Summer 2 This Pack is designed for 8 hours worth of learning. What does this mean? You will be revising the topics that you have been taught so far. These include: 1. Reactions of metals 2. Energy For each topic, use the resources in this pack. What do I need to know for these units? See the knowledge organisers, If you have access to the textbook (Activate Book 1 and Activate Book 2) on Kerboodle, use that too. You can also find additional resources online (KS3 Bitesize and Seneca learning) Which words do I need to understand and use? Task: Go through the knowledge organizer for each topic, pick out the keywords. Add these to your glossary with a definition and use each one in a sentence. You might be able to use several words in one sentence.) What do I need to know about these topics? Once you have completed your learning, complete the questions included in this pack in worksheets. How can I show that I understand this really well? Complete the questions for each lesson. Check your answers using the answers provided at the end of each topic. You should be able to conduct the practical from lesson 5 (Food and fuels) as this uses food nutrition packs you will probably have at home. Send your completed work back to your teacher for further feedback.
Transcript
Year 8 Science Home Learning PackSummer 2
This Pack is designed for 8 hours worth of learning.
What does this mean? You will be revising the topics that you have been taught so far. These include:
1. Reactions of metals2. Energy
For each topic, use the resources in this pack.
What do I need to know for these units? See the knowledge organisers, If you have access to the textbook (Activate Book 1 and Activate Book 2) on Kerboodle, use that too. You can also find additional resources online (KS3 Bitesize and Seneca learning)
Which words do I need to understand and use? Task: Go through the knowledge organizer for each topic, pick out the keywords. Add these to your glossary with a definition and use each one in a sentence. You might be able to use several words in one sentence.)
What do I need to know about these topics?Once you have completed your learning, complete the questions included in this pack in worksheets.
How can I show that I understand this really well?Complete the questions for each lesson. Check your answers using the answers provided at the end of each topic.You should be able to conduct the practical from lesson 5 (Food and fuels) as this uses food nutrition packs you will probably have at home.
Send your completed work back to your teacher for further feedback.
ContextLesson 1 and 2- Reacting metals with acidsSetting the scene When metals react with acids they form a salt and hydrogen. But not all metals react readily with acid. You will use the signs of a reaction to identify which metals react more readily, and which react least readily.
Lesson 3 and 4 - Comparing the reactivity of metalsSetting the scene The reactivity series is a list of metals that shows metals in order of how reactive they are. Reactive metals can react with cold water and dilute acids. Less reactive metals can only react with warm water and concentrated acids.
Lesson 5 and 6 - Displacement reactionsIn a displacement reaction a more reactive metal takes the place of a less reactive metal in a compound.
Lesson 7 and 8 - How are metals extracted?Setting the scene
You are going to answer questions about how metals are extracted, complete a reactivity series, and then predict how certain metals could be extracted. Read 7.4.1 Extracting metals in your student book to help answer the questions.
Lesson 1 and 2 - Reacting metals with acidsSetting the scene When metals react with acids they form a salt and hydrogen. But not all metals react readily with acid. You will use the signs of a reaction to identify which metals react more readily, and which react least readily.
HypothesisWhat are the products of a reaction of a metal with an acid?
PredictionWhat will you see during the reactions?
Method1 Fill a third of a test tube with hydrochloric acid.2 Place a small piece of magnesium ribbon into the acid.3 Place an empty test tube upside down over the test tube containing the acid.4 Wait for one minute to collect any gas produced.5 Remove the test tube and, with the test tube still upside down, hold a lit splint to the
mouth of that test tube.6 Record all your observations from the reaction and the test for hydrogen.7 Repeat the method using zinc, lead, and iron.Results
Questions1 List the observations that suggested a chemical reaction was occurring.
2 List the four metals in order of increasing reactivity with the acid (starting with the least reactive metal). Explain how you decided the order they should be in.
3 Describe how you tested that the gas produced was hydrogen gas.
4 Complete the following word equations for the reactions between the four metals and the hydrochloric acid:
magnesium + hydrochloric acid →
zinc + hydrochloric acid →
lead + hydrochloric acid →
iron + hydrochloric acid →
Extension 1 Suggest why it is unsafe to collect too much hydrogen gas before testing it with a lit
splint.
2 Suggest why you used similar sized pieces of each metal and the same amount of acid in each reaction.
Lesson 3 and 4 - Comparing the reactivity of metalsSetting the scene The reactivity series is a list of metals that shows metals in order of how reactive they are. Reactive metals can react with cold water and dilute acids. Less reactive metals can only react with warm water and concentrated acids.
Questions1 Use your observations to state the order of reactivity for sodium, copper and
magnesium, starting with the most reactive. Explain your answer.
2 Write the word equations for the reactions of sodium with water and with acid.
3 Using your observations and the reactivity series in the student book, predict how:a calcium will react with cold waterb lead will react with acid.Explain your answers.
4 List any variables that you controlled and identify any that were difficult to control.
5 Two of the metals you are testing may both react in the same way (such as both reacting with dilute acid). Suggest a way that you could still compare the two metals to find out which was more reactive.
Extension
1 Suggest why a thermometer has been included as a possible piece of apparatus for your investigation.
2 Write a paragraph about why it is important to consider the cost as well as the reactivity of metals when choosing which to use for different functions. Include examples in your answer.
Lesson 5 and 6 - Displacement reactions
Word Pronunciation Meaningdisplace When one element takes the place of
another element in a compound.displacement reaction
A reaction where a more reactive element takes the place of a less reactive element in a compound.
In a displacement reaction a more reactive metal takes the place of a less reactive metal in a compound.
1 A piece of grey zinc was placed in a beaker of blue copper nitrate solution. After 1 week, the remaining metal was a pink/brown colour and the solution was colourless.
a Give the name of the:
pink/brown metal ____colourless solution_____
b Write the word equation for this reaction.
_______________________________________________
2 Answer the questions by putting a tick () in the box next to each correct statement. a Iron displaces copper from copper sulfate solution. From this information,
it can be deduced that …
copper is more reactive than iron. iron is more reactive than copper.
b Magnesium displaces silver from silver nitrate solution. From this information, it can be deduced that …
magnesium is more reactive than silver.
silver is more reactive than magnesium.
3 Three metals, A, B and C, were added to the oxides of metals A, B and C and heated. None of the metals was added to its own metal oxide. The results are shown in the table.
Metal oxide Metal A Metal B Metal C Oxide of metal A reaction no reaction Oxide of metal B no reaction no reaction Oxide of metal C reaction reaction
a Give the letter of the most reactive metal. ___ b Give the letter of the least reactive metal. _______
Here is the solution to a crossword. Write clues for the answers.
You will need to write Across clues 1, 3, 9, 10 and Down clues 2, 4, 5, 6, 7, 8.
When you have finished your clues, pass them to someone else to try out your crossword.
Lesson 7 and 8 - How are metals extracted?
Setting the scene You are going to answer questions about how metals are extracted, complete a reactivity series, and then predict how certain metals could be extracted. Read 7.4.1 Extracting metals in your student book to help answer the questions.
AimsIn this activity you will: describe the two processes used to extract metals from their compounds
describe how Earth’s resources are turned into useful materials
justify the choice of an extraction method for a metal.You will be using enquiry processes to: Communicate: communicate scientific ideas effectively
Analyse: construct explanations
Communicate: justify opinions
Task1 Complete this table by writing definitions of the key words.
Key word Definition
Natural resource
Mineral
Ore
Extraction
Recycling
Electrolysis
2 How are metals below carbon in the reactivity series extracted?
5 Complete this reactivity series with these labels:potassium; copper; iron; calcium; aluminium; zinc; most reactive; least reactive; extracted using carbon; extracted by electrolysis
_____________ →
___________________
sodium
magnesium
carbon
___________________tinlead
_____________ →
6 How would you extract these metals?
a sodium ___________________________
b copper ___________________________
c magnesium ___________________________
d iron ___________________________
Key questionsKey Question 1: Describe how you would test for hydrogen gas. What result would you expect?
Key Question 2: Complete these word equations of metals and hydrochloric acid:magnesium + hydrochloric acid zinc + hydrochloric acid copper + hydrochloric acid
Key Question 3: Describe how you would compare the reactivity of iron and zinc using hydrochloric acid.
Key Question 1: What are the state symbols for solids, liquids and gases?
Key Question 2: Write the word and balanced symbol equation for the reaction of magnesium and oxygen, including state symbols.
Key Question 3: Explain how we know that iron is less reactive than magnesium.
Key Question 1: What do you observe when alkali metals react with water?
Key Question 2: Write the word and balanced symbol equation for the reaction of sodium and water.
Key Question 3: Explain how we know that potassium is more reactive than lithium.
Key Question 1: What are the three parts of a PEE paragraph when writing your conclusion?
Key Question 2: What are two rules of writing a good method?
Key Question 3: How would you compare the reactivity of lead and calcium?
Key Question 1: Which is more reactive; zinc or tin? Use the reactivity series.
Key Question 2: Describe what a displacement reaction is.
Key Question 3: Complete the word equation for the chemical reaction below:zinc oxide + aluminium
Key Question 1: Pyrite is an iron ore that contains 10% iron. How much iron can you extract from 80g of pyrite?
Key Question 2: Explain how to extract iron from iron oxide.
Key Question 3: Explain why carbon cannot be used to extract aluminium from aluminium oxide.
Key Question 1: State two uses of ceramics.
Key Question 2: Describe the physical properties of ceramics.
Key Question 3: Explain why ceramics have a high melting point.
Questions1 (most reactive) calcium, magnesium, iron, and copper (least reactive)
(If calcium was hard to ignite, this can appear to be less reactive than magnesium – this should be discussed with students.)
2 Students should explain that that the reaction started more quickly with more reactive metals and seemed to transfer more energy to the surroundings, for example, bright light is produced.
3 There was more oxygen available as it wasn’t part of a mixture, unlike in air. Hence it is easier for the magnesium to find oxygen to react with.
Extension1 Reactive means how easily an element undergoes reactions. More reactive
elements will react more easily.2 An example answer could be:
Magnesium is more reactive than iron, but less reactive than calcium.I know this because iron only glowed when it was burnt in oxygen but magnesium burnt very quickly and with a bright white flame, showing it is more reactive. Calcium also burnt brightly, but seemed to have a brighter flame.
3 Lithium is more reactive than calcium, magnesium, iron, and copper. The reaction of lithium with oxygen is more violent than the reaction of these other metals with oxygen in a Bunsen burner flame. The reaction would start more quickly and transfer more energy to the surroundings. For example, calcium only produced a bright light, whereas lithium is explosive.
Lesson 2 - Answers - Comparing the reactivity of metals1 (most reactive) sodium, magnesium, copper (least reactive)2 sodium + water → sodium hydroxide + hydrogen
sodium + hydrochloric acid → sodium chloride + hydrogen3 a Calcium will react with water more vigorously then magnesium and copper, but
less than sodium.
b Lead will react with acid more vigorously than copper, but less than magnesium
and sodium.4 Any appropriate control variables from their method (e.g., volume of acid/water
used, mass of metal pieces, temperature) and detail on those that were difficult to control (e.g., how vigorously the gas bubbled is subjective, hard to tell when all the metal has been used up if there are lots of bubbles in the solution).
5 The time taken for the metal to be used up could be recorded, or the temperature change in the reaction could be monitored.
Extension 1 The temperature of the water affects the reactivity of some of the metals. It is
important to keep the temperature the same for each experiment, so as to get an accurate idea of the reactivity series of these three metals.
2 It is important to know the reactivity of metals as it can help you to predict how a metal will behave. For example, gold is known to be an unreactive metal. This makes it suitable for use in items such as jewellery. Copper is known to be
unreactive with water, so it is suitable for use in copper pipes carrying water. If you know a chemical is very reactive this can let you know that it will react very violently, so extra safety precautions will be needed. The cost of the metal is important to consider alongside the reactivity because although gold is very unreactive, it is also very expensive. This means it would be a poor choice for something where a large quantity is needed (e.g., water pipes). (Allow any reasonable description, with examples, of the importance of cost and reactivity when considering which metal to use.)
Lesson 3 - Answers - Displacement reactions1 a pink/brown metal is copper; colourless solution is zinc nitrate b zinc + copper nitrate → copper + zinc nitrate
2 a iron is more reactive than copper b magnesium is more reactive than silver
3 a B b C
Lesson 4 - Answers – Extracting metals1 Example definitions:
Key word Definition
Natural resources Materials from the Earth which act as raw materials for making a variety of products
Mineral Naturally occurring metal or metal compoundOre Naturally occurring rock containing sufficient minerals for extractionExtraction Separation of a metal from a metal compoundRecycling Processing a material so that it can be used againElectrolysis Using electricity to split up a compound into its elements
2 Heating with carbon, which displaces the metal as it is more reactive.3 Electrolysis4 Electrolysis is expensive because the rock needs to be molten, so it is heated to very high
temperatures, which requires a lot of energy.5 See next page.
most reactive → potassium
extracted by electrolysis
sodium
calcium
magnesium
aluminium
carbon
zinc
extracted using carbon
iron
tin
lead
least reactive → copper
6 electrolysis; carbon; electrolysis; carbon
Answers to Key questions
Key Question 1: Describe how you would test for hydrogen gas. What result would you expect?Expected answer: 1. Put a lit splint into the gas2. If hydrogen is present then a squeaky pop sound will be heardKey Question 2: Complete these word equations of metals and hydrochloric acid:magnesium + hydrochloric acid zinc + hydrochloric acid copper + hydrochloric acid Expected answer: magnesium + hydrochloric acid à magnesium chloride + hydrogenzinc + hydrochloric acid à zinc chloride + hydrogencopper + hydrochloric acid à copper chloride + hydrogenKey Question 3: Describe how you would compare the reactivity of iron and zinc using hydrochloric acid.Expected answer:Add the same volume of hydrochloric acid to the same mass of metal and observe how many bubbles are made. The metal that makes the most bubbles
is the most reactive.
Key Question 1: What are the state symbols for solids, liquids and gases?Expected answer: Solid = (s)Liquid = (l)Gas = (g) Must be lower case.Key Question 2: Write the word and balanced symbol equation for the reaction of magnesium and oxygen, including state symbols.Expected answer: Magnesium + oxygen à magnesium oxide 2 Mg (s) + O2 (g) à 2 MgO (s)Key Question 3: Explain how we know that iron is less reactive than magnesium.Expected answer:Iron reacts more slowly with oxygen than magnesium doesIron reacts more slowly with acid than magnesium does – less hydrogen bubbles produced]Key Question 1: What do you observe when alkali metals react with water?Expected answer: They fizz and move around on the surface of the water. Sodium makes yellow flames. Potassium makes purple flames. Rubidium and caesium explode in water.Key Question 2: Write the word and balanced symbol equation for the reaction of sodium and water.Expected answer: Sodium + water à sodium hydroxide + hydrogen 2 Na + 2 H2O à 2 NaOH + H2Key Question 3: Explain how we know that potassium is more reactive than lithium.Expected answer:Potassium fizzes more vigourously than lithium in water, suggesting that it is more reactive.Potassium produces flames in water, whereas lithium does not, suggesting that it is more reactive.Key Question 1: What are the three parts of a PEE paragraph when writing your conclusion? Expected answer: P – point, E – evidence, E - explanationKey Question 2: What are two rules of writing a good method?Expected answer: numbered steps, refer to all equipment, exact amounts, include control variables, include how to measure the dependent variableKey Question 3: How would you compare the reactivity of lead and calcium?Expected answer: add the same amount of metal to the same amount of acid and observe how many bubbles are produced. The most reactive metal produces the most bubbles.
Key Question 1: Which is more reactive; zinc or tin? Use the reactivity series.Expected answer: ZincKey Question 2: Describe what a displacement reaction is.Expected answer: When a more reactive element displaces a less reactive element during a chemical reaction.Key Question 3: Complete the word equation for the chemical reaction below:zinc oxide + aluminium àExpected answer:zinc oxide + aluminium àaluminium oxide + zinc
Key Question 1: Pyrite is an iron ore that contains 10% iron. How much iron can you extract from 80g of pyrite?Expected answer: 10% of 80 g = 8 gKey Question 2: Explain how to extract iron from iron oxide.Expected answer: Heat it up with carbon.Carbon displaces iron to react with the oxygen, producing iron.Key Question 3: Explain why carbon cannot be used to extract aluminium from aluminium oxide.Expected answer:Aluminium is more reactive than carbon, so heating with carbon would not cause a displacement reaction.
Key Question 1: State two uses of ceramics.Expected answer: Bricks, potteryKey Question 2: Describe the physical properties of ceramics.Expected answer: Strong, hard, brittle, stiff, have very high melting points, strong, insulatorsKey Question 3: Explain why ceramics have a high melting point.Expected answer:Ceramics have many strong bonds between atoms which require a lot of energy to break.
Lesson 5 - Food and fuelsSetting the scene We take in energy from food we eat and use it on activities like moving, keeping warm, and speaking. In this activity you will compare the energy needed for certain activities and the energy supplied by different foods.
AimsIn this activity you will:
compare the energy of different foods compare the energy of different activities.
You will be using enquiry processes to:
Analyse: present information and data in tables Communicate: explain how our food intake should match our activity levels.
TaskEnergy is measured in joules (J). You need 10 J of energy to lift a 1 kg bag of sugar from the floor and put it on a table. The table below lists some other activities and the energy they use.1 Add three more examples of the energy used for different activities, either by using
these ideas or from other sources of information.
Activity Energy used (J)
Energy in kilojoules (kJ)
Rank order
Walking for 10 minutes 150 000Running for 10 minutes 750 000Climbing a flight of stairs 2000Lifting a school bag 100A baby sleeping for one hour 10 000Lighting a room for four hours 864 000Heating a microwave meal 200 000Recharging a mobile phone 500Heating bath water 294 000 000Heating a room for four hours 28 800 000
A joule is too small a unit to be useful so energy on food labels, and other amounts of energy, is described in kilojoules (kJ). 1 kJ = 1000 J.2 Fill in the column of the table above to show the energy in kilojoules. 3 Fill in the final column to show which activity uses the most energy, where 1 =
activity using the most energy.4 Collect a selection of food labels from six different foods. You will find lots of different
types of food packets in your kitchen cupboards.5 Fill in the table below showing the energy provided per 100 g of food.6 Add information about the energy per portion of food to your table.
Type of food Energy per 100 g Energy per portion
QuestionsThe table below lists the daily energy requirements of people at different ages and activity in kJ.
Daily energy requirement (kJ)
when mainly resting when very active
primary-school boy 6 400 9 200
secondary-school boy 9 900 14 400
young adult man 10 300 14 800
middle-aged adult man 9 900 14 200
elderly man 8 300 11 900
1 State the person who uses the least energy per day, using the data above. Explain why this is the case.
2 State the person who uses the most energy per day using the data above. Explain why this is the case.
3 Describe what happens if you take in more food than you need for your daily energy requirement.
4 Estimate the daily energy requirement for a secondary-school girl who is fairly active. Show your working.(Note: females use approximately 13% less energy than males of the same age.)
5 Use the information from the food labels to suggest what you could eat to supply your energy requirement.
Extension Write a paragraph describing how the energy requirements of an athlete training for the Olympics would change as the hours of training increase, and suggest ways their diet should allow for this.
Lesson 6 - Energy resources
Setting the scene We use many different fuel sources for electricity, transport, and heating. In this activity you will find out more about how we use different fuel sources and produce a poster or leaflet explaining what happens.
AimsIn this activity you will: describe the difference between a renewable and a non-renewable energy
resource describe how fossil fuels are formed describe how electricity is generated in a power station.
You will be using enquiry processes to: Enquire: collect information from a range of sources Communicate: present information to the rest of the class Solve: identify risks of using different energy resources.
TaskYou are going to carry out research using books and leaflets to find out about the following things:
description and examples of renewable energy resources description and examples of non-renewable energy resources description and examples of fossil fuels detailed description of how one type of fossil fuel was formed description of the processes inside a fossil-fuel power station, including the jobs of:o the furnace
o the boiler
o the turbine
o the generator
problems with generating electricity from fossil fuels.You will then produce a poster or a leaflet on the ideas above and present this to the rest of the class.
ExtensionExplain whether your choice of resources used during your research is reliable. Think about potential bias in the material you used.You may wish to include in your poster or leaflet a discussion of the advantages and disadvantages of using renewable energy resources.
Lesson 7 – Power
Powerful equipment does a job very quickly compared with other equipment. You will learn about the power of different pieces of equipment and how to calculate the energy they transfer.You will then use what you have learnt to compare the running costs of fluorescent and filament light bulbs.
AimsIn this activity you will: explain the difference between energy and power compare the running costs of fluorescent and filament light bulbs.
You will be using enquiry processes to: Analyse: interpret data to analyse patterns and make conclusions. Analyse: discuss the limitations of your conclusions Communicate: construct and communicate explanations Communicate and Solve: check and evaluate another student’s claims and
explain your reasoning Solve: consider the environmental and cost consequences of using different light
bulbs.
InformationThis table shows the approximate brightness of several different light bulbs.
Light bulb Light bulb type Power in watts
Brightness in lumens
A filament 60 600
B halogen 28 360
C CFL 15 600
D LED 4 180
E CFL 20 1100
F filament 25 180
G LED 10 600
H halogen 42 600
Questions
1 Use the information in the table to list the light bulbs in order of power, starting with the most powerful.
2 Explain the difference between energy transfer and power, using their definitions.
3 Raj states that “The filament light in my bedroom is 60W and is dimmer than the 100W filament light in the living room. So the more powerful a light bulb, the brighter it is.”Use the table above to decide if Raj’s statement is always true. Explain your answer.
4 Calculate the energy used by a 0.011 kW lightbulb in 1 minute.Use the formula:energy (J) = power (W) × time (s)
5 Electricity bills depend on the amount of energy transferred. Powerful equipment transfers a lot of energy per second.Write down the cheapest and most expensive light bulbs to use in your house.
6 State any problems with your answer to question 5. Hint: Think about the brightness of the light that the light bulbs emit.
7 a Calculate the running costs of a filament lamp with a 60 W bulb and a CFL lamp with a 15 W bulb for 15 hours.
1 kWh costs 10p.
cost = power (kW) × time (hours) × price (per kWh)
b Which type of bulb is cheaper to run?
c Both bulbs emit the same amount of light. Use what you observed in the demonstration to explain the answer to 7b.
8 Compare the effect of everyone switching from filament to CFL light bulbs on the environment.
Extension 1 An electrical company charges 15 p per unit of energy (kWh).
Calculate the cost of running a 500 W freezer for a day. Show your working.
2 Here is some information about power of equipment and the time they are switched on for in a typical day. A homeowner would like to reduce the size of their electricity bill. Suggest some changes they could make. Explain your answer.
Equipment Power (kW) Time switched on
kettle 1.2 30 min (1/2 hour)
heater 2 5 hours
lights 0.1 5 hours (usually six lights are used)
TV 0.5 4 hours
computer 0.5 1 hour
oven 3 1 hour
fridge 0.1 24 hours
hairdryer 1 15 min (1/4 hour)
power shower 2 15 min (1/4 hour)
The conservation of energyIdentify which energy store is used at the start and end of each set up by circling the correct words in bold in the table. Also use the table to record your observations for each experiment.
Experiment Description of experimental set-up Energy store at start Observations Energy store at end
1lifting a mass using a motor powered by a battery
chemical / kinetic gravitational / thermal
2 a swinging pendulum gravitational / chemicalfirst transferred to a kinetic / elastic store and then a gravitational store
3 rolling a toy car down a ramp gravitational / elastic elastic / kinetic
4 a battery-operated fan thermal / chemical gravitational / kinetic
5releasing a pull-back toy car elastic / chemical kinetic / thermal
6 lighting a candle thermal / chemical gravitational / thermal
Hint: Moving objects have a kinetic energy store. Hot objects have a thermal energy store.
Lesson 8 - Investigating the efficiency of light bulbsSetting the scene A large percentage of the electricity we use is for lighting our homes. Different types of lightbulb are useful for different purposes and in different places in the house.
AimsIn this activity you will:
calculate useful and wasted energy using input and output energies rank a range of different bulbs in terms of their efficiency.
You will be using enquiry processes to:
Analyse: select relevant data and carry out calculations.
InformationThis table provides data for some different light bulbs. You will use this data to answer the questions that follow.
Light bulb type
Input energyin joules
Useful output energy
in joules
Wasted energy
in joules
Percentage efficiency
Rank
filament 3600 108
CFL 300 39
filament 1500 60
CFL 900 99
Questions1 Calculate the wasted energy for each bulb. Fill in the table with your answers.
2 State the formula for efficiency. (You may use the student book to help you.)
3 Use the formula for efficiency to calculate the percentage efficiency of each bulb. Fill in the table with your answers and rank them from 1 to 4 in terms of efficiency.
4 Describe what is meant by efficiency.
5 Suggest reasons why some bulbs are more efficient than others. Use this answer and your answer to Question 4 to explain why you cannot have a bulb that is 100% efficient.
Extension A 60 W energy-saving bulb is switched on for one minute. If it is 12.5% efficient, calculate the energy output of this bulb as light. Show your working.Hint: energy (J) = power (W) × time (s)
Key questions on Energy topic
Key Question 1: State what unit energy is measured in.
Key Question 2: Predict what happens to a woman who has an energy output of 3100 kJ and eats 2900 kJ stored chemical energy in food.
Key Question 3: Explain why an athlete needs a greater energy input from food than the average person.Expected answer:
Key Question 1: State the ‘law of conservation of energy’.
Key Question 2: State the different types of energy stores.
Key Question 3: Describe the energy transfers that take place when an electric car accelerates.
Key Question 1: State how temperature is measured and the units.
Key Question 2: Describe what happens to particles in solids, liquids and gases as they reach a higher temperature.
Key Question 3: Describe how an electric kettle heats up water.
Key Question 1: Explain a difference between an insulator and a conductor.
Key Question 2: Describe how a long metal pole conducts heat from one end to the other.
Key Question 3: Explain how a convection current happens in a saucepan of water as it heats up.
Key Question 1: Complete this sentence. ‘A hypothesis is a statement that tries to explain something based on…’
Key Question 2: Explain why air is a poor conductor of heat.
Key Question 3: State which was the poorest conductor in your investigation and explain why.
Key Question 1: Which objects emit infrared radiation?
Key Question 2: Explain the difference between absorbing and emitting infrared radiation. Use examples.
Key Question 3: Explain why a shiny foil blanket keeps you warm.
Key Question 1: Name some renewable energy sources.
Key Question 2: How is electricity generated from coal?
Key Question 3: Decide whether one coal power station or 100 wind turbines should be built to provide
enough energy for a new town. Give a reason for your choice.
Key Question 1: Explain what the power rating of a microwave tells you and what the units are.
Key Question 2: If Power = energy ÷ time, calculate the power of a microwave that transfers 2000 joules of energy in 20 seconds.
Key Question 3: Explain why using light bulbs that have a low power rating will reduce the electricity bill.
Key Question 1: What does ‘work done’ mean?
Key Question 2: If Work = force x distance, calculate the work done on a book that is pushed 1 m with a force of 5 N, including units.
Key Question 3: How does a lever make it easier to lift things?
Answers – Lesson 5 – Food and FuelsActivity sheetTaskAgain, table shows order of the activities given. Students should have estimated a further three activities and ranked them appropriately.
Activity Energy used (J)
Energy in kilojoules (kJ)
Rank order
Walking for 10 minutes 150 000 150 6Running for 10 minutes 750 000 750 4Climbing a flight of stairs 2000 2 8Lifting a school bag 100 0.1 10A baby sleeping for 1 hour 10 000 10 7Lighting a room for 4 hours 864 000 864 3Heating a microwave meal 200 000 200 5Recharging a mobile phone 500 0.5 9Heating bath water 294 000 000 294 000 1Heating a room for 4 hours 28 800 000 28 800 2
The table of food type with energy per 100g and per portion will be dependent on the food labels provided.Questions1 Primary-school boy – Smallest individual so needs less energy for use in living
processes.2 Young adult man – Largest individual who is also the most active so will need more
energy.3 If you take in more food than you need for your daily energy requirement, you will
gain weight.4 14 400 ÷ 100 = 144
144 × 13 = 1 87214 400 – 1 872 = 12 528 kJ
5 This answer depends on the food labels used. However, it should seem reasonable compared with what the students (and you) eat in a day.
ExtensionTypical information to include is that the athlete is training for hours each day. They are pushing themselves to their limit so will be very active. An athlete needs to increase their food intake as their hours of training increase. However, they should balance this with sensible eating habits to ensure they don’t get ill, for example, if they have too much sugar or fat, or are exercising on a very full stomach, and so on.
Answers – Lesson 6 – Energy resources
In this activity, students produce a leaflet or a poster on renewable and non-renewable energy using information from their research from different sources. As this task is less structured, there are no specific answers but there follows a guideline of the sorts of points that should be included. Encourage students to think about presentation in this task, and credit them for it, as leaflets and posters should not contain blocks of text.1 Renewable energy resources, non-renewable energy resources, and fossil fuels A renewable energy resource is an energy resource that can be replaced/will not run out. A non-renewable energy resource is an energy resource that will run out/cannot be
replaced soon. Renewable energy resources – biomass, hydroelectricity, tides, wind, geothermal, wood Other non-renewable energy resources – nuclear A fossil fuel is an energy resource that formed millions of years ago from dead plants and
animals. Fossil fuels formed when tiny plants/animals died and were buried in the sea/swamps
under layers of other materials/mud. Over millions of years, the dead plants/animals changed into fossil fuels.
Fossil fuels (non-renewable) – coal, oil, natural gas
2 The main parts of a fossil fuel power station The furnace is used to burn the fossil fuels. The boiler is used to heat water, turning it into steam. The turbine spins when steam passes over it/turns the generator. The generator is used to generate electricity when it spins.
3 Generating electricity from fossil fuels Problems with using fossil fuels include: they will run out; they cause global warming. This is because they take millions of years to replace/create carbon dioxide when burnt. Advantages of using fossil fuels include: they are reliable; they produce a lot of electricity. This is because they can be used whenever they are needed/are concentrated
energy resources. On the activity sheet, students may be able to provide more detail, and choices of energy
resources may differ in some answers.
The extension should explain that the advantages of renewable energy resources are they will not run out/can be replaced in our lifetime/may be free to use (for example, wind)/some do not create carbon dioxide (however, biomass and biofuels do).
Disadvantages are that they can be unreliable (dependent on weather or the time of day) and are the equipment may be expensive compared to non-renewable energy resources.
Answers – Lesson 7 - PowerQuestions1 A, H, B, F, E, C, G, D
If students fill in the table then answers depend on the light bulbs provided.2 Energy transfers are the changes in temperature or work. Power is how much energy
is transferred per second. It is the rate of transfer of energy.3 Students Raj’s statement is not true because CFL/halogen/LED light bulbs with the
same/less power than filament light bulbs are as bright/brighter. Students should use examples from the table to justify their answer.
4 energy (J) = power (W) × time (s)0.011 kW × 1 000 = 11 W1 minute = 60 seconds11 W × 60 s = 660 JNote unit conversion required.
5 Cheapest = D, most expensive = AIf students fill in the table then answers depend on the light bulbs provided.
6 Students should realise that the cheapest bulb is less bright than the most expensive bulb so you might need many more bulbs in the house, which would increase the cost.
7 a 60 W bulb60 W ÷ 1000 = 0.06 kWcost = 0.06 kW × 15 × 10
= 3pb CFL bulbc The CFL bulb is cheaper to run because it is less powerful so it transfers less
energy. The filament bulb transfers more energy even though it emits the same amount of light because it heats the bulb and surrounds more than the CFL bulb.
8 Students should realise that if everyone uses light bulbs with lower power then less energy would be needed so less fuel burned in power stations.
Extension
1 500 W ÷ 1 000 = 0.5 kW0.5 × 24 = 1212 × 15 = 180 p or £1.80
2 Examples: Some things contribute more to the bill, for example, the heater, TV, and oven. Some equipment needs to be left on (fridge). Make sure energy-efficient bulbs are used or unnecessary lights are turned off. Use heating for a shorter time or use less powerful heaters.
Answers - Lesson 8 – Conservation of energyExperiment 1: Start – chemical; End – gravitational Experiment 2: Start – gravitational; End – first kinetic and then gravitationalExperiment 3: Start – gravitational; End – kinetic Experiment 4: Start – chemical; End – kinetic Experiment 5: Start – elastic; End – kinetic Experiment 6: Start – chemical; End – thermal
Answers - Lesson 8 - Investigating the efficiency of light bulbs
Light bulb type
Input energyin joules
Useful output energy
in joules
Wasted energy
in joules
Percentage efficiency
Rank
filament 3600 108 3492 3% 4
CFL 300 39 261 13% 1
filament 1500 60 1440 4% 3
CFL 900 99 801 11% 2
Questions1 wasted energy (energy dissipated) = energy input – useful energy output
See table for answers.
2 efficiency (%) = useful energy output×100energy input
3 See table for answers.
4 Efficiency measures the proportion of energy dissipated when energy is transferred to a device. The higher the proportion of dissipated energy, the lower the efficiency of a device.
5 Some bulbs are more efficient than others as some bulbs transfer more energy to light the room than to heat the surroundings. A bulb cannot be 100 % efficient as some energy will always be transferred to heat the surroundings (dissipated).
Extension 1 energy input = power × time = 60 × 60 = 3600 J
Answers – Key questionsKey Question 1: State what energy is measured in.Expected answer: Joules (J)Kilojoules (kJ)Key Question 2: Predict what happens to a woman who has an energy output of 3100 kJ and eats 2900 kJ stored chemical energy in food.Expected answer: She will burn fat and lose weightBecause she needs 200 kJ more to meet her energy needs for her activitesKey Question 3: Explain why an athlete needs a greater energy input from food than the average person.Expected answer:They have a greater output of energy from activities when training as an athlete, therefore they need more energy input.
Key Question 1: State the ‘law of conservation of energy’.Expected answer: Energy cannot be created or destroyed, only transferred between different energy stores.Key Question 2: State the different types of energy stores.Expected answer: Chemical, thermal, kinetic, gravitational potential, elasticKey Question 3: Describe the energy transfers that take place when an electric car accelerates.Expected answer:Energy transfers from the battery chemical store into the kinetic energy store as it moves.
Key Question 1: State how temperature is measured and the units.Expected answer: Using a thermometer, in °CKey Question 2: Describe what happens to particles in solids, liquids and gases as they reach a higher temperature.Expected answer: They move faster in gases and liquids and vibrate more in a solidKey Question 3: Describe how an electric kettle heats up water.Expected answer:- The hot kettle transfers thermal energy to the cold water- This transfer stops when equilibrium is reached - When the kettle and water are the same temperature
Key Question 1: Explain a difference between an insulator and a conductor.Expected answer: An insulator only allows thermal energy to travel slowly through it whereas a conductor allows thermal energy to travel quickly through it.An insulator as clothes or in a house reduce heat loss as compared to a conductor.Key Question 2: Describe how a long metal pole conducts heat from one end to the other.Expected answer: Where heated, the particles vibrate moreThis increased vibration is passed onto nearby particles until all are vibrating moreKey Question 3: Explain how a convection current happens in a saucepan of water as it heats up.Expected answer:- The heat from the saucepan transfers thermal energy to water particles at the bottom so they move faster- These particles move further apart so are less dense- The less dense hotter water floats up above the more dense, colder water
Key Question 1: Complete this sentence. ‘A hypothesis is a statement that tries to explain something based on…’Expected answer: Something that has been observed / results of an investigationKey Question 2: Explain why air is a poor conductor of heat.Expected answer: Air is a gas so the particles are far apart and cannot pass on the vibrations during conductionKey Question 3: State which was the poorest conductor in your investigation and explain why.Expected answer: e.g. bubble wrap, because it has little pockets of air and air is an insulator.
Key Question 1: Which objects emit infrared radiation?Expected answer: All objects emit infrared radiation.Key Question 2: Explain the difference between absorbing and emitting infrared radiation. Use examples. Expected answer: Absorbing means to take in - Your body absorbs infrared radiation from the sun, causing it to warm up and an infrared imaging camera absorbs infraredEmitting means to give out – all objects emit infrared radiation, some hotter objects emit more infrared radiation.Key Question 3: Explain why a shiny foil blanket keeps you warm.Expected answer:- Shiny surfaces reflect infrared radiation- The foil blanket reflects the infrared radiation emitted from the body, back to the body- This keeps you warm
Key Question 1: Name some renewable energy sources. Expected answer: Wind, tidal, wave, biomass, solar, hydroelectric, geothermalKey Question 2: How is electricity generated from coal?Expected answer: Burning coal produces steam. Steam drives a turbine. The turbine drives a generator. The generator generates electricity.Key Question 3: Decide whether one coal power station or 100 wind turbines should be built to provide enough energy for a new town. Give a reason for your choice.Expected answer:Coal – produces a lot of energy in all weathers and the turbines depend on weatherTurbines – wind is a renewable energy source and coal will run out. There is no pollution made, unlike coal
Key Question 1: Explain what the power rating of a microwave tells you and what the units are.Expected answer: Power tells you how much energy is transferred per second or the rate of energy transferWatts (W) Kilowatts (kW)Key Question 2: If Power = energy ÷ time, calculate the power of a microwave that transfers 2000 joules of energy in 20 seconds.Expected answer: Power = energy ÷ timePower = 2000 ÷ 20Power = 100 WKey Question 3: Explain why using light bulbs that have a low power rating will reduce the electricity bill.Expected answer:A lower power rating means that less energy is transferred per second to get the same outputTherefore less electricity will be used
Key Question 1: What does ‘work done’ mean?Expected answer: the transfer of energy when a force moves an object in joules.Key Question 2: If Work = force x distance, calculate the work done on a book that is pushed 1 m with a force of 5 N, including units.Expected answer: Work = force x distance Work = 5 x 1Work = 5 joulesKey Question 3: How does a lever make it easier to lift things?Expected answer: By increasing the force which increases the work done.
