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Chemical reactions part 1
 

Chemical reactions part 1

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  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit: © 2008 Jupiterimages Corporation
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Chemical Reaction (Part One) Worksheet 1 accompanies this slide.
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit (top left): Jan Kratěna Photo credit (top centre): © 2008 Jupiterimages Corporation Photo credit (top right): © 2008 Jupiterimages Corporation Photo credit (bottom left): © 2008 Jupiterimages Corporation Photo credit (bottom centre): Ove Tepfer Photo credit (bottom right): © 2008 Jupiterimages Corporation
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit: © 2008 Jupiterimages Corporation
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Teacher notes: This illustration contains several discussion points relating to areas of chemical research, including: pesticides to protect crops materials for medical implants biodegradable plastics detergents that work at low temperatures smart paints that can change colour materials for solar panels . This slide could be used to prompt a discussion of the importance of different types of chemical research, or to start a chemical research activity into recent developments in these areas. This slide could also be used to give pupils an idea of the impact of chemistry in everyday life, and could be used to prompt discussion or research of chemistry careers.
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit: Lorenzo González
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit: © 2008 Jupiterimages Corporation
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit: © 2008 Jupiterimages Corporation
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit: Craig Jewell Teacher notes This slide could be used as an introduction to an investigation into how to prevent apples from browning. For example, students could look at which substances stop pieces of apple from browning, such as vitamin C, orange juice, citric acid solution, etc.
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit: Lotus Head
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit: Alexander Daucik
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Photo credit: Jean Scheijen
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Chemical Reactions (Part One) Worksheet 2 accompanies this slide.
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Teacher notes Copper carbonate (CuCO 3 )  copper oxide (CuO) + carbon dioxide (CO 2 )
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One) Glossary chemical reaction – A change in which new substances are made and which cannot easily be reversed. products – The new substances produced in a chemical reaction and shown on the right of a word equation. reactants – The starting substances used in a chemical reaction and shown on the left of a word equation. word equation – A summary of a chemical reaction.
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)
  • Boardworks KS3 Science 2008 Chemical Reactions (Part One)

Chemical reactions part 1 Chemical reactions part 1 Presentation Transcript

  • 1 of 40 © Boardworks Ltd 2008
  • 2 of 40 © Boardworks Ltd 2008
  • Safety precautionsWhen scientists carry out experiments, they have to takesafety precautions. This is to make sure that they minimize therisk of harming themselves, other people and the environment.What kind of safetyprecautions shouldyou take in the lab?What kind of safetyprecautions shouldchemists working inindustrial labs take? 3 of 40 © Boardworks Ltd 2008
  • What are hazard symbols?When working in a lab, how can you tell which chemicals aresafe and which are dangerous?Hazard labels are used on containers and vehicles thatcontain dangerous chemicals. toxic irritant harmful corrosive flammableThese hazard symbols show why the chemical is dangerous.Why is it important that symbols are used, rather than words? 4 of 40 © Boardworks Ltd 2008
  • What do hazard symbols mean? 5 of 40 © Boardworks Ltd 2008
  • What do hazard symbols mean? 6 of 40 © Boardworks Ltd 2008
  • 7 of 40 © Boardworks Ltd 2008
  • Everyday reactionsChemical reactions happen all around us, not just in the lab. cooking sticking burning making materials rusting livingCan you think of more everyday chemical reactions? 8 of 40 © Boardworks Ltd 2008
  • How can you spot a chemical reaction?Lots of changes happen in chemical reactions.You might recognize that a chemical reaction is happeningbecause the substances involved: change colour give off a gas get hot get cold give out light make smells form solids. 9 of 40 © Boardworks Ltd 2008
  • Chemical reactions are hard to reverseChemical reactions are usually difficult to reverse.For example, magnesium burns in oxygen to form magnesiumoxide. It is not at all easy to ‘un-burn’ the magnesium once ithas been burnt. magnesium + oxygen ² magnesium oxideMany reactions need an input of energy to get them started.This is called activation energy.Many reactions (like the burning of magnesium) also releaseenergy once the reaction has started. 10 of 40 © Boardworks Ltd 2008
  • Odd-one-out 11 of 40 © Boardworks Ltd 2008
  • Non-useful chemical reactionsChemical reactions in food causeit to decay, making it unsafe to eat.Chemical reactions like these area nuisance, but other reactionscan even be dangerous.The reaction between iron andoxygen causes the metal to becomerusty, which weakens the structureand makes it dangerous to use.Factories sometimes produce waste gases that pollute theatmosphere. These gases cause acid rain and mightcontribute to the greenhouse effect. 12 of 40 © Boardworks Ltd 2008
  • Useful chemical reactions 13 of 40 © Boardworks Ltd 2008
  • More useful chemical reactionsChemists carry out chemical reactions to produce newsubstances that improve people’s lives. 14 of 40 © Boardworks Ltd 2008
  • The chemistry of foodThere are many chemical reactions involved in our food: howmany can you think of? cooking ripening fruit food going mouldy making fertilizers and pesticides photosynthesis for plants to grow digestion when you eat food fermentation to make bread, beer and wine. 15 of 40 © Boardworks Ltd 2008
  • CookingCooking involves chemical reactions. Changes in colour, tasteand texture are due to the molecules in food joining together innew ways.Cooking anegg changesits texture fromrunny to firm.Eggs contain a protein called albumen. The protein moleculesare long chains of amino acids folded into a ball shape.When eggs are heated, some of the proteins break apartand the molecules unfold. These molecules then join to othernearby protein molecules until they are all linked in a network. 16 of 40 © Boardworks Ltd 2008
  • Making bread and alcoholYeast is a living organism that carries out the chemicalreactions that are used for making bread and alcohol.Yeast uses oxygen from the air for aerobic respiration. sugar + oxygen ² carbon dioxide + water C6H12O6 6O2 6CO2 6H2OWhat effect do you think the carbon dioxide gas has on thebread?Yeast can also carry out respiration without oxygen. This iscalled anaerobic respiration, or fermentation. This is used toproduce the alcohol in beer and wine. 17 of 40 © Boardworks Ltd 2008
  • Ripening fruitThe ripening of fruit is a complex collection of chemicalreactions. Take apples as an example: Starch is broken down into sugars, increasing sweetness. Acids are neutralized, making the apples less sour. Chlorophyll (green) changes to anthocyanin (red). Pectin, a chemical that makes apples hard, is broken down, making the apples softer.Why do food producers and supermarkets need to knowabout the conditions and reactions involved in ripening fruit? 18 of 40 © Boardworks Ltd 2008
  • What causes ripening?The ripening of all fruit and vegetables involves similar chemicalreactions.The speed of ripening is affected bythe temperature and by the presenceof a chemical called ethene, C2H4.Food scientists can tell producersand supermarkets the bestconditions for slowing down orspeeding up the ripening processso that fruit and vegetables arrivein the shops perfectly ripe. 19 of 40 © Boardworks Ltd 2008
  • Food spoilageThe changes that take place as food ‘spoils’ are also causedby chemical reactions.For example, peeled apples turn brown when exposed tothe air because they react with oxygen in the air.Knowing what causes this reactioncan help to slow it down.Placing sliced apples in waterprevents browning because theapples are no longer exposed to air.The chemical ascorbic acid (vitamin C), which is found inlemon juice, is also known to prevent the browning reaction. 20 of 40 © Boardworks Ltd 2008
  • Chemistry and cleaningGrease and oil on clothing, cutlery, skin and hair are difficultto remove with just water, because oil and water do not mix.Adding soap allows the oil and water to mix.Soap moleculeshave two ends: head of moleculeone end is bonds to waterattracted to the moleculeswater molecules;the other end is tail of moleculeattracted to the bonds to oiloil molecules. molecules 21 of 40 © Boardworks Ltd 2008
  • Chemistry and cosmeticsThe ingredients in cosmetics like makeup, shampoo and faketan are made by chemical reactions. Many of the ingredientsin these products are made from crude oil.Is it sustainable to use ingredients like these? 22 of 40 © Boardworks Ltd 2008
  • Chemistry and medicineThe medicines that we take are all made by chemists. Manymedicines started out as natural products, which came fromliving things: aspirin – from the bark of willow trees penicillin – from mould morphine – from poppies digoxin – from foxgloves.Do you know what thesemedicines are used for?What do you think might be the advantages and disadvantagesof using drugs from plants and moulds? 23 of 40 © Boardworks Ltd 2008
  • Chemistry and computersMaterials scientists are chemists who research new materialsfor things like computers.screen – togive out light electric wires –casing – made of tough, to carrymouldable plastic electricity silicon chips – topaints and inks – for the store and transferletters on the keys information 24 of 40 © Boardworks Ltd 2008
  • Reactants and productsIn a chemical reaction, one or more new substances arealways formed.The starting substances used in a reaction are the reactants.The new substances formed in a reaction are the products. reactants productsThe arrow means ‘change into’. In a chemical reaction, thereactants change into the products.It is often difficult to reverse a chemical reaction and changethe products back into the reactants. 25 of 40 © Boardworks Ltd 2008
  • Word equationsA word equation is a quick, shorthand way of writing a chemicalreaction.There are always three parts to a word equation: the names of the reactants an arrow the names of the products.What is the word equation for hydrogen reacting with oxygento form water? hydrogen + oxygen ² water 26 of 40 © Boardworks Ltd 2008
  • Reactant or product?In this chemical reaction, which substances are the reactantsand which substances are the products? copper magnesium magnesium + oxide ² oxide + copper substance reactant or product? magnesium oxide product magnesium reactant copper oxide reactant copper product 27 of 40 © Boardworks Ltd 2008
  • Write the word equations 1. Magnesium burns brightly in oxygen to form magnesium oxide. magnesium + oxygen ² magnesium oxide 2. Calcium hydroxide reacts with hydrochloric acid to form calcium chloride and water. calcium hydrochloric calcium hydroxide + acid ² chloride + water 3. Sodium reacts with hydrochloric acid to form sodium chloride and hydrogen. hydrochloric sodium sodium + acid ² chloride + hydrogen 28 of 40 © Boardworks Ltd 2008
  • 29 of 40 © Boardworks Ltd 2008
  • Mass during a reaction 30 of 40 © Boardworks Ltd 2008
  • Why doesn’t the mass change?In chemical reactions, no atoms can be made or destroyed.Chemical reactions just change how the atoms are bondedtogether. + + 31 of 40 © Boardworks Ltd 2008
  • What happens to the mass? 32 of 40 © Boardworks Ltd 2008
  • Why did the mass increase?In the reaction between magnesium and oxygen, the massincreased.This is because the magnesium atoms joined up with oxygenatoms. ² +What is the word equation for this reaction? magnesium + oxygen ² magnesium oxide 33 of 40 © Boardworks Ltd 2008
  • What happens to the mass? 34 of 40 © Boardworks Ltd 2008
  • Why did the mass decrease?The mass of the copper carbonate decreasedas it was heated because it decomposed toform copper oxide and carbon dioxide.What is the word equation for this reaction?Why did the mass decrease?The mass decreased because the carbondioxide gas escaped out into the air.Can you calculate the massof carbon dioxide that wasproduced in the reaction? 35 of 40 © Boardworks Ltd 2008
  • Chemical reactions – true or false? 36 of 40 © Boardworks Ltd 2008
  • 37 of 40 © Boardworks Ltd 2008
  • Glossary 38 of 40 © Boardworks Ltd 2008
  • Anagrams 39 of 40 © Boardworks Ltd 2008
  • Multiple-choice quiz 40 of 40 © Boardworks Ltd 2008