Doc Brown's KS3 Chemistry

KS3 SCIENCE-Chemistry QCA Unit 7F Simple chemical reactions

KS3 Quizzes or task sheets based on this 7F summary: four word-fill worksheets * multiple choice quiz * X-word

More advanced GCSE work based on 7F GCSE m/c tests * Acids, Bases, Neutralisation & Salts notes * Oil Products-fuels notes * Chemical Tests * Types of Chemical Reaction * Elements & Compounds notes

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KS3 Chemistry Quiz - 7F Simple chemical reactions  KS3 Chemistry Quiz - 7F Simple chemical reactions  KS3 Chemistry Quiz - 7F Simple chemical reactions QCA 7F "Simple chemical reactions" Multiple Choice Questions for Science  revision on idea of chemical reaction (reactants => products), new materials, acid + metal/carbonate reaction, burning/combustion reaction.

KS3 Chemistry word-fill worksheets - 7F Simple chemical reactions 7Fwf1-4 four handy linked word-fill worksheets * 7Fwf2 * 7Fwf3 * 7Fwf4 *

The BIG hard on-line crossword puzzle KS3 Chemistry 7F Simple chemical reactions crossword puzzle BIG (with letter hints), printout of the BIG version

OR the smaller EASIER KS3 Chemistry 7F Simple chemical reactions crossword puzzle SMALL (with letter hints), printout of the smaller EASIER version

The 7F crossword and word-fill KS3 Chemistry 7F Simple chemical reactions answers to word-fill worksheets and crossword puzzles

* KS3 Science multiple Choice Quizzes for chemistry, worksheets and practice chemistry questions for pupils revising Key Stage 3 science  tests revision help for secondary students *

Advanced Chemistry Page Index and Links

In this unit you should learn how to ...

  • see that chemical changes result in new material substances that are different from the ones from which they were made
  • explore some simple chemical reactions of acids in which a gas is made
  • explore burning as a chemical reaction involving a gas, air or oxygen
  • identify hydrogen and carbon dioxide gases as real materials made during some of these reactions
  • begin to use word equations as shorthand descriptions of reactions
  • learn techniques for testing for gases, using laboratory equipment effectively and safely
  • investigate the role of air in the burning of a candle
  • generalise that hydrogen is formed when acids react with metals; carbon dioxide when acids react with carbonates; oxides form when materials burn as they react with oxygen
  • describe tests for carbon dioxide and hydrogen and describe burning as a reaction with oxygen

Its handy to  ...

  • know that there are many gases
  • have explored changes in which new materials are formed and which cannot easily be reversed
  • have used the pH scale as a measure of acidity and alkalinity

Some important words for you to understand, use and spell correctly

  • names of gases, eg hydrogen, oxygen, carbon dioxide, methane
  • names of other elements and compounds, eg carbon, zinc, calcium carbonate
  • words and phrases describing chemical reactions, eg reactant, product, word equation
  • words and phrases relating to scientific enquiry, eg line graph, generalisation, evaluate

What is a chemical reaction?

  • to make and interpret observations of chemical reactions to recognise new substances formed
  • everyday materials which react chemically when they are mixed, eg lemon juice and bicarbonate of soda, baking powder and water, plaster of Paris and water
  • describe typical observed changes, eg it bubbled, it felt warm, changes colour
  • generalise that when bubbles are formed a gas is released and this is a new material

How do acids react with metals?

  • how to carry out a lit splint test for hydrogen
  • that acids can be corrosive and corrode metals like magnesium and zinc easily - bubbling to!
  • generalise that when an acid is added to many metals new substances eg hydrogen are produced and the metal disappears (reacts - dissolves!) or becomes smaller to form another substance
  • relate the disappearance of the metal to the idea of corrosion
  • the terms ‘reactant’ and ‘product’ (what you start with, what you end up with!)
  • what happens when a range of acids is added to a range of metals?  make generalisations from the results eg hydrogen always seems to be formed from the chemical change
  • identify that some metal(s), eg copper, do not react with acids to produce hydrogen

How do acids react with carbonates?

  • what the ‘fizz’ in bottled water is - identify the gas as carbon dioxide and demonstrate how to collect carbon dioxide and test for it using limewater.
  • what happens with samples of carbonates, possibly including ...
    • rocks, eg chalk, building materials, marble
    • or household materials, eg baking powder, carbonate indigestion remedies
  • generalise that when an acid is added to a carbonate, carbon dioxide is made and is evidence of a chemical reaction producing new substances

What new substances are made when materials burn in air or oxygen?

  • burning requires oxygen and new substances, usually oxides, are formed when materials burn in air or oxygen (beware of hazards - intense fast reaction)
  • introduction to the idea of word equations as shorthand for simple combustion reactions eg
    • substance + oxygen (reactants) ==> oxides (products)
  • information about fire prevention and firefighting
  • test the pH of the oxide produced and to demonstrate that the product of burning carbon turns lime water cloudy.

What is produced when fuels burn?

  • that fuels are substances that release energy when they burn
  • that fossil fuels are rich in compounds containing carbon form carbon dioxide on burning
  • that natural gas is called methane, and carbon dioxide and water are produced when it burns, and these substances are also formed when wax, ethanol ('alcohol') and wood burn too
  • is it likely that carbon dioxide and water could be turned back into fuel? NO but plants do it!
  • more word equations: methane + oxygen ==> water + carbon dioxide + heat energy
  • energy is NOT a material

What is needed for things to burn?

  • which part of the air is used up during burning?
  • the effect of putting a large glass container over a lighted candle floating on a trough of water and how do we explain what we see?
  • What was in the large container?; Why did the candle go out?; Why didn’t it go out immediately?; Why did the water rise up the container?; What is made when a wax candle burns?; What happens to this?
  • explain that the candle goes out when oxygen is used and why the water rose up the container

Advanced Chemistry Page Index and Links

 Doc Brown's Chemistry Revision  KS3 Science CHEMISTRY Unit 7F Simple chemical reactions

KS3 Chemistry Quiz - 7F Simple chemical reactions QUIZ 7F "Simple chemical reactions"

What the Quiz is based on - original work schemes - programmes of study

All of KS3 Science is now under review

and the quizzes will be adapted to suit the NEW National Curriculum for KS3 Science

About the unit

In this unit pupils:

  are introduced to the idea that chemical change results in new substances that are different from the ones from which they were made

  explore some simple chemical reactions of acids in which a gas is made

  explore burning as a chemical reaction involving a gas, air or oxygen

  identify hydrogen and carbon dioxide as substances made during some of these reactions

  work with gases to understand that gases are real materials

  begin to use word equations as shorthand descriptions of reactions

In scientific enquiry pupils:

  learn techniques for testing for gases, using laboratory equipment effectively and taking action to control risks

  present observations in ways which enable patterns to be seen

  make generalisations from observations

  suggest and evaluate explanations of observations

  investigate the role of air in the burning of a candle

This unit is expected to take approximately 7 hours.

Where the unit fits in

This unit uses ideas developed in the key stage 2 programme of study. It builds on ideas introduced in unit 5C ‘Gases around us’ and unit 6D ‘Reversible and irreversible changes’ in the key stage 2 scheme of work.

This unit relates closely to unit 7E ‘Acids and alkalis’ and these can be used together as an introductory unit in year 7, in which pupils use equipment and techniques they may not have encountered in key stage 2.

An approach to teaching about energy is included in the Teacher’s guide and in the ‘About the unit’ section of unit 7I ‘Energy resources’.

Unit 9E ‘Reactions of metals and metal compounds’ and unit 9F ‘Patterns of reactivity’ include further work on the reactions of acids and on burning as a chemical change. Unit 9H ‘Using chemistry’ includes work on the conservation of mass in chemical reactions, including burning.

Expectations

At the end of this unit

in terms of scientific enquiry

most pupils will: obtain and present qualitative results, identifying patterns in these; work safely with acids and when burning materials; suggest how to test an idea about burning, obtaining results which can be represented as a line graph

some pupils will not have made so much progress and will: obtain and present qualitative results, describe some hazards of acids and of burning; work safely with acids and when burning materials; test an idea about burning and present results

some pupils will have progressed further and will: evaluate how well ideas about burning match the data collected

in terms of materials and their properties

most pupils will: identify that some new materials are formed during a chemical reaction and generalise that hydrogen is formed when acids react with metals, carbon dioxide when acids react with carbonates, and oxides when materials burn; describe tests for carbon dioxide and hydrogen and describe burning as a reaction with oxygen

some pupils will not have made so much progress and will: identify some products of chemical reactions and state that oxygen or air is needed for burning

some pupils will have progressed further and will: predict that carbon dioxide and water will be made when a hydrocarbon burns and use word equations to represent reactions in which materials burn

Prior learning

It is helpful if pupils:

  know that there are many gases

  have explored changes in which new materials are formed and which cannot easily be reversed

  have used the pH scale as a measure of acidity and alkalinity


Health and safety

Risk assessments are required for any hazardous activity. In this unit pupils:

  work with acids

  observe materials burning in oxygen

  burn liquid fuels

  plan their own investigation into burning a candle

Model risk assessments used by most employers for normal science activities can be found in the publications listed in the Teacher’s guide. Teachers need to follow these as indicated in the guidance notes for the activities, and consider what modifications are needed for individual classroom situations.

Language for learning

Through the activities in this unit pupils will be able to understand, use and spell correctly:

  names of gases, eg hydrogen, oxygen, carbon dioxide, methane

  names of other elements and compounds, eg carbon, zinc, calcium carbonate

  words and phrases describing chemical reactions, eg reactant, product, word equation

  words and phrases relating to scientific enquiry, eg line graph, generalisation, evaluate

Through the activities pupils could:

  collaborate with others to share information and ideas, and solve problems

  group sentences into coherent paragraphs with subheadings as appropriate

Resources

Resources include:

  corroded metals

  building materials including carbonate rocks, eg chalk, marble

  carbonated water

  computer and software to produce information leaflet

  cards on which are written words, phrases and statements about chemical reactions

Out-of-school learning

Pupils could:

  visit a fire station open day to hear talks and see fire-prevention displays

  consider how burning is used in celebrations, eg candles, bonfires, fireworks


 

    What is a chemical reaction?

   to make and interpret observations

   Provide pairs of pupils with everyday materials which react chemically when they are mixed, eg lemon juice and bicarbonate of soda, baking powder and water, plaster of Paris and water. Ask pupils to mix them and make as many observations as they can. Ask pupils to decide and give their reasons for whether a new material has been made. Explain that in each case a chemical reaction has taken place and that in this unit they will find out more about other chemical reactions and what new substances are made.

  describe changes, eg it bubbled, it felt warm

  generalise that when bubbles are formed a gas is released and this is a new material

   In key stage 2 many pupils will have explored changes in which new materials are made (unit 6D ‘Reversible and irreversible changes’) but are less likely to have classified the changes as chemical reactions.

     How do acids react with metals?

   how to carry out a test for hydrogen

   that acids can be corrosive

   that acids react with some metals to produce new substances, including hydrogen

   Remind pupils of earlier descriptions of acids as corrosive and show some examples of corroded metals. Establish through a quick class experiment that when an acid is added to a metal, eg zinc, magnesium, bubbles are made.

   Demonstrate an appropriate method for testing the gas produced and explain that a gas behaving in this way is hydrogen.

  describe and carry out the lighted splint test for hydrogen

  generalise that when an acid is added to many metals, hydrogen is produced and the metal disappears or becomes smaller

  relate the disappearance of the metal to the idea of corrosion

   In key stage 2, pupils are likely to have seen reactions of acids producing a gas (unit 6D ‘Reversible and irreversible changes’) and have encountered common gases (unit 5C ‘Gases around us’). However, they will not have tested or identified gases produced.

   It may be helpful to introduce the terms ‘reactant’ and ‘product’.

Safety  

– eye protection should be used. 0.4 mol dm-3 acid is suitable. Acids are not necessarily corrosive and most of those encountered by pupils will not be

   to record relevant observations

   to identify and describe patterns in qualitative data

   to identify results which do not appear to fit the pattern 

   Ask pupils to investigate what happens when a range of acids is added to a range of metals and to record and make generalisations from their results.

   Bring together pupils’ results and establish that in most cases a new material, hydrogen, is made, showing that there was a chemical reaction between the acid and the metal.

  use a table to present observations in a way which enables patterns to be seen

  identify metal(s), eg copper, which do not react with acids to produce hydrogen

  conclude that when hydrogen was made a chemical reaction had taken place

   At this stage, it is sufficient for many pupils to identify that acids react with many metals to produce hydrogen. Some teachers may wish to take this further, either by considering what other products are obtained or by considering patterns in reactivity. This is more fully covered in unit 9F ‘Patterns of reactivity’.


 

    How do acids react with carbonates?

   how to carry out a test for carbon dioxide

   to produce new substances, including carbon dioxide

   to identify and describe patterns in qualitative data

   to generalise from their observations

   Ask pupils what the ‘fizz’ in bottled water is. Identify the gas as carbon dioxide and demonstrate how to collect carbon dioxide and test for it using lime water.

   Provide pupils with samples of carbonate, possibly including rocks, eg chalk, building materials, eg marble, household materials, eg baking powder, carbonate indigestion remedies, and ask them to investigate the effect of adding a range of acids to these and to record and make generalisations from their results. Establish that in each case a chemical reaction took place and draw out the idea that chemical reactions are important.

  carry out and describe the lime water test for carbon dioxide

  generalise that when an acid is added to a carbonate, carbon dioxide is made

  use a table to present observations in a way which enables patterns to be seen

  conclude that the production of carbon dioxide is evidence of a chemical reaction

   It may be helpful to emphasise that the colourless gas (carbon dioxide) collected in this activity is a different material and behaves differently from the gas collected in the previous activity.

   The effects of acid rain on carbonate building materials are covered in unit 8G ‘Rocks and weathering’.

Safety

– eye protection should be worn when lime water is in use

– eye protection should be used.
0.4 mol dm
-3
acid is suitable


 

    What new substances are made when materials burn in air or oxygen?

   that burning requires oxygen

   that new substances, usually oxides, are formed when materials burn

   to use appropriate scientific terminology and conventions

   how to carry out combustion reactions safely

   to identify and note key points

   to group sentences into coherent paragraphs with subheadings as appropriate

   Demonstrate burning some elements in air and then in oxygen. Emphasise the hazards of burning materials in oxygen. Use secondary sources to illustrate more hazardous reactions. Show pupils how to burn materials safely in oxygen. Ask pupils to describe what they see and point out to them that in each case the new material is an oxide and that a chemical reaction has taken place.

   Introduce the idea of word equations for simple combustion reactions and ask pupils to sort cards showing reactants and products to produce word equations.

   Ask pupils to use secondary sources to find information about fire prevention and firefighting and to produce information sheets, eg for use in the home, explaining key principles.

  describe, eg through producing word equations, burning as a reaction in which a material reacts with oxygen to produce an oxide

  name the products of some reactions

  explain precautions that need to be taken when burning materials and why more care is needed if materials are burnt in oxygen 

  identify key points about fire safety

  express key points clearly in a structured way 

   In key stage 2, pupils will have considered burning as an irreversible change (unit 6D ‘Reversible and irreversible changes’). However, they are unlikely to have considered it in terms of combination with oxygen.

   Some teachers may wish to test the pH of the oxide produced and to demonstrate that the product of burning carbon turns lime water cloudy.

   At this stage word equations are used as shorthand. Teachers may wish to postpone their introduction for some pupils. Units 8E, 8F, 9E, 9F, 9G and 9H deal more fully with equations.

   This activity could be ICT-based.

Safety  

– eye protection should be worn by teachers and pupils, who should be seated 2m away. Employer’s risk assessments on the use of elements such as sulphur, phosphorus and magnesium should be consulted


 

    Checking progress

   that new materials are made during chemical reactions

   that the products of a reaction can be deduced from the reactants

   Provide pupils with a series of cards showing words or phrases about the chemical reactions, eg reactant, product, metal, acid, carbonate, oxide, carbon dioxide, hydrogen, oxygen, and ask them to group them into three sets to describe the three types of chemical reaction covered in the unit. Help them to use the words or phrases to make generalisations about the three types of reaction.

  identify a product of each type of reaction

  make generalisations about the products of each type of reaction

 

    What is produced when fuels burn?

   that fuels are substances that release energy when they burn

   that fossil fuels are rich in compounds containing carbon

   that burning fossil fuels results in the production of carbon dioxide

   that natural gas is called methane, and carbon dioxide and water are produced when it burns

   Elicit pupils’ ideas about fuels by asking them what they understand by the term and what examples they can give of fuels. Explain that fossil fuels are rich in carbon and ask pupils to suggest what might be formed when they burn.

   Demonstrate that carbon dioxide (and water) is produced when methane burns. If possible, extend the demonstration by using other fuels containing hydrogen and carbon, eg wax, ethanol, wood. Discuss with pupils whether it is likely that carbon dioxide and water could be turned back into fuel.

   Help pupils make a summary of information about burning fossil fuels.

  name a range of fuels and explain the meaning of the
term ‘fuel’

  generalise that carbon dioxide
is produced when
carbon-containing fuels burn

  summarise burning of methane in a word equation

   The formation of fossil fuels and burning of fuels to release energy is covered in unit 7I ‘Energy resources’. In this unit teachers may wish to concentrate on identifying the products of burning.

   Pupils often think that energy, like gas, is a material and has mass.

   Environmental effects of burning fossil fuels are covered later in unit 9G ‘Environmental chemistry’.

Safety

– employer’s risk assessments on the use of fuels should be followed. Eye protection should be worn. Small quantities of fuels should be used and storage bottles kept well away from where the fuels are burnt


 

    What is needed for things to burn?

   that part of the air is used up during burning

   to suggest and evaluate explanations

   to suggest how to test an idea

   to produce a line graph from results and to draw conclusions from these

   to collaborate with others to share information and ideas, and to solve problems

   Show pupils the effect of putting a large glass container over a lighted candle floating on a trough of water and ask questions to help them explain what happens, eg
– What was in the large container?

Why did the candle go out?
Why didn’t it go out immediately?
– Why did the water rise up the container?
– What is made when a wax candle burns?
– What happens to this?

   Ask pupils in groups to work out explanations. Help them to evaluate their explanations through questioning and establish that part of the air was used up and that the candle could not continue to burn. Link back to earlier work on comparing burning in air and oxygen.

   Extend by asking pupils to investigate the idea that the candle goes out when part of the air is used up. Help them to turn this into a question that can be tested and to devise a way of getting results from which a graph can be plotted.

  explain that the candle goes out when oxygen is used up

  suggest and evaluate ideas about why the water rose up the container

  generalise that the less oxygen there is the sooner the candle would go out and suggest a way of testing this

  draw a line graph of results; describe what it shows, relating this to the oxygen available for burning

  contribute usefully to group work

   This activity provides an opportunity for pupils to suggest their own ideas and to think critically about these and the ideas of others. Teachers may wish to go into detail with some pupils about factors such as expansion of air on heating and solubility of carbon dioxide, but it is not necessary to do so.

   Extension: pupils could be asked to find out about earlier work on burning and oxygen by scientists, eg Lavoisier, Priestley.

Safety  

– use candles that are short and difficult to knock over and ensure they are set in a firm base. Teachers should check pupils’ plans for health and safety before practical work begins

    Reviewing work

   to identify key points about reactions of acids with metals, acids with carbonates and burning

   to group points together to make a summary

   Provide pupils with a series of statements, or ask them to make their own, about the areas covered in the unit. Ask them to work together to choose the most helpful statements for a summary and to group those chosen into four or five main sections. Ask pupils to explain why they chose or rejected particular statements and agree an overall summary with them.

  identify statements which are helpful to a summary

  combine statements into a summary

  give reasons for choosing or rejecting particular statements

 

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