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Using this booklet

When you see this symbol it means you have some reading to do.

When you see this symbol it means you have an activity or an experiment to do.

When you see this symbol it means you have a writing task to do.

When you see this symbol you will have an internet research task.

You will be using many chemicals in this topic. Read this page before you start and refer to it when these symbols appear on the bottles of chemicals you are using. Handle all chemicals with great care. Always wash your hands after using chemicals.

Hazard warning symbols

This shows that the chemical is corrosive.

These chemicals can cause burns to the skin, as well as holes in some metal objects. Acids are corrosive chemicals

This shows that the chemical is flammable (this means the same as inflammable).Flammable chemicals catch fire and burn very easily.

This shows that the chemical is harmful or irritant. Chemicals with this warning symbol can make you feel very unwell by affecting your skin or organs. In many cases your lungs or breathing system can be damaged by these chemicals.

This shows that a chemical is an oxidizer. This means it could cause irritation if in contact with skin.

1. Introduction to Chemical Reactions

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In this lesson you will be introduced to chemical reactions and the fact that they always produce a new substance.

Ask your teacher to show the DVD(13) on Chemical Reactions

Chemical Reactions

Chemical changes occur all the time in the world around us. When the particles in some chemicals come into contact they can react to make new chemicals. Scientists call this a chemical reaction. If a chemical reaction happens a new substance is always formed.

The new chemicals have very strong bonds holding them together. This means: It is very difficult to reverse a chemical reaction.

Here are some examples of everyday chemical reactions you know:

●Toasting bread

●Fireworks going off

●Digesting food

●Striking a match

Experiment 1Demo- Chemical Reactions

Watch the following demonstrations and look for signs that a new substance has formed.

(i)Magnesium burning in air

(ii)Calcium + water

Write the heading “Chemical Reactions” and answer the following questions in sentences:

1. When the particles in some chemicals come into contact they can ______to form ______.

2.Scientists call this a c______r______.

3. In a chemical reaction a ______is always formed.

4. It is difficult to reverse a chemical reaction because ______.

5. When the magnesium burned in air, I knew a chemical reaction had occurred because ______

6. A new substance was/was notformed when calcium was added to water. The evidence to show this was ______

7. Give some examples of some chemical reactions you know below:

______

Teachers checkpoint

2.Identifying a chemical Reaction

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In this part of the topic we will look at some chemical reactions in more detail and identify the signs that show that a chemical reaction has occurred.

Signs of a Chemical Reaction

In every chemical reaction there is always a tell tale sign that a reaction has taken place and that a new substance has been formed. Here are the 4 signs we should look for:

●A change in colour – e.g. A rusting car

● A gas being made (bubbling or a smell) - e.g. A rotting egg

● A solid being formed – e.g. Milk going off

● Heat or light being given out– e.g. A firework or any kind of

burning like coal, wood or petrol.

Experiment 2 Notice any Change?

The aim of the next experiment is to find out if a chemical reaction has occurred when 2 substances are mixed.

Before going to your work station you must follow the following instructions:

  1. Collect your results handout. Put the heading “Signs of a Chemical Reaction” in your jotter and write down the aim of the experiment on the sheet.
  2. Complete the table on it as you do each experiment.
  3. Collect the equipment and chemicals you will need:

●Safety goggles

●3 clean small test tubes

●A spatula

●A dropper

●A test-tube rack

●Thermometer (For experiment 2)

●The chemicals listed in your table.

IMPORTANT: ●Wash out all test-tubes between each

experiment.

●Once you have used the chemicals return them

the trolley as other groups will need them.

4. Once you have completed all the experiments tidy all your

apparatus away.

Questions

Answer all the following questions in sentences.

  1. The four signs of a chemical reaction are;

i) ______

ii) ______

iii) ______

iv) ______

  1. Write down an example of a chemical reaction for each sign.

i)______

ii) ______

iii) ______

iv) ______

Teachers checkpoint

Extension: Ask your teacher to show you the powerpoint “Is it a chemical reaction”. With your elbow partner decide whether or not a chemical reaction is taking place. Remember a new substance must be produced for it to be a chemical reaction.

  1. Reactants and Products

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In this part of the topic we are going to look more closely at the make up of chemical reactions in terms of reactants and products.

Read

Making new chemical products is a very important job for scientists. They take starting materials and using chemical reactions changes the starting materials into new useful products.

Collect a copy ofSpotlight Science book 2 and go to page 70. Look at the picture of the kitchen. What materials have scientists helped to make through chemical reactions? Write a list. For example, glass for windows.

List:______

Teachers checkpoint

Combining!

A chemical reaction involves two or more chemicals (called reactants) combining together to form one or more new substances (called products) usually with energy being released. When two or more different elements react together the products are called compounds.

These new substancesare chemically joined and are very difficult to separate.

Experiment 3Demonstration: Making the Compound Iron Sulphide

Your teacher will now show you a demonstration of a chemical reaction where the reactants iron and sulphur are heated and react to form the product iron sulphide. The demonstration should also show you that the new compound is very difficult to separate.

Answer the following questions in sentences:

1.The starting materials in all chemical reactions are called ______.

2. The new substances in allchemical reactions are known as ______.

3. New substances (compounds) are easy/hard to separate.

Copy and complete the following sentences:

Before heating, the iron and sulphur are easy to s______using a magnet. This is because the are only mixed and not c______j______.

The heat causes a c______r______to occur and the iron and sulphur chemically join to form the compound i______s______. This compound iseasy/hard to separate.

Teachers checkpoint

Extension: Spotlight Science 2 Page 71, Q3 – Yellow box.

4.Formation of Compounds

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In this part of the topic we will reveal more about the products of a chemical reaction and how elements can combine to form compounds.

Read

In First Year you learned that elements have only one type of atom. Iron is made up of only iron atoms and oxygen is only made up of oxygen atoms.

Compounds are the products of chemical reactions. Compounds have 2 or more different atoms chemically joined together. For example Iron sulphide is made up of iron and sulphur atoms.

Experiment 4Demo: The Formation of the Compound Water

Your teacher will now show you a demonstration of a chemical reaction which forms the compound hydrogen oxide (water).

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Before attending the demo look closely at the diagram of the experiment and also the table below. Complete the table during the experiment. The reactants are the starting materials and the product is the resultant new substance.

Reactants / Product

Questions:

  1. I knew a chemical reaction had occurred because ______.
  2. Copy and complete the following:

When the reactants hydrogen and oxygen are burned together the p______of the reaction is a compound called h______o______. This compound is also known as w______.

Teachers checkpoint

5. Chemical Reactions: Testing for Gases

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In this part of the topic we are going to use chemical reactions to tell the difference between the gases oxygen, hydrogen, carbon dioxide and nitrogen.

Read

In every chemical reaction reactants turn into new substances called products. As we know, these new substances can sometimes be bubbles of gas.

There is a problem though. These gases tend to be colourless, so we don’t know what gases they are.

Luckily, scientists have found a way of identifying these gases. We can do experiments, called chemical tests, to identify the gases.

Experiment 5 Testing For Gases

You are about to do an experiment which will allow us to identify 3 of the following 4 gases. Read the instructions carefully before and during the experiment.

Complete the following table as you do the experiment.

Gas / Test
Limewater / Glowing Splint / Burning Splint
Nitrogen
Oxygen
Carbon Dioxide
Hydrogen

Apparatus:

Collect from the trolley: 3 test tubes of oxygen

Some limewater

Wooden splint

Small measuring cylinder

Collect from the cupboard:A Bunsen burner and heat mat

Safety goggles

Test tube rack

Instructions:

  1. Light the Bunsen, but leave it on a yellow safety flame.
  2. Use the Bunsen to light the wooden splint.
  3. Remove the stopper from one of the test tubes and slowly push the lit splint into it. Record your observations in the table.
  4. Light the splint again but this time blow the flame out leaving the splint glowing.
  5. Remove the stopper from one of the test tubes and place the glowing splint into it. Record your observation in the table.
  6. Take the lime water and measure out 5cm3 using the measuring cylinder.
  7. Remove the stopper from the final test tube of oxygen and add in the 5cm3of limewater. Replace the stopper and shake the test tube for 5 seconds. Record your observations in your table.
  8. Repeat steps 1-7 for three test tubes of nitrogen, hydrogen and carbon dioxide

Teachers checkpoint

Use the information from the experiments to copy and complete the following:

Chemical Tests

If a glowing splint is put into a test tube of ______gas, the splint will re-light.

If limewater is put into a test tube of ______gas, the limewater will turn ______.

If a burning splint is put into a test tube containing hydrogen a ____ will be heard as the gas burns.

Questions:

  1. Oxygen/carbon dioxide is best for extinguishing fires because ______
  2. Nitrogen is not a good fuel because ______2 gases that would be good fuels are ______and ______.
  3. When zinc metal is added to acid the gas produced burns with a pop. The name of this gas is ______.
  4. When hydrogen peroxide decomposes (breaks up) the gas given off will re-light a glowing splint. The name of the gas is ______.
  5. When acid is added to calcium carbonate the gas given off will turn limewater cloudy. The name of this gas is ______.

Teachers checkpoint

6.Everyday Chemical Reactions

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In this lesson we will discuss chemical reactions which occur in our everyday lives.

You will already know about, or will soon find out about some reactions like respiration in our bodies and fermentation (formation of alcohol). In this section we will look at another two everyday chemical reactions.

Burning Fuels – A Useful Reaction?

Your teacher may show you a DVD(51 or76) on Burning.

A fuel is a substance which burns in oxygen gas to give us energy. Burning, or Combustion as it is also known as, is a chemical reaction. This burning reaction which gives out energy is called an exothermic reaction. Exothermic reactions always give out energy like heat or light. All combustion reactions are exothermic. When fuels burn they also give compounds containing oxygen, which are called oxides.

Most fuels are made up of the elements carbon and hydrogen. This means that when they burn in oxygen they give us oxides of carbon and hydrogen, usually carbon dioxide and hydrogen oxide (water).Examples of fuels are coal, petrol natural gas, wood, diesel and peat.

Why do we need fuels?

Writes down a list of the ways we use fuels.

As you can see we need to burn fuels for a variety of reasons like heating our homes and powering our cars. So combustion is an important reaction.

Questions

  1. A fuel is something that ______in ______to produce ______.
  2. The gas needed for fuels to burn is ______.
  3. Another name for burning is ______.
  4. The special name given to reactions which give out energy is ______reactions.
  5. As well as energy, the other products made when a fuel burns are c______d______and w______.
  6. Copy and complete the word equation:

Fuel + ______→ ______+ ______+ Energy

______

Teachers checkpoint

Internet Research

Carbon dioxide gas is always produced when fuels burn. This gas is called a GREENHOUSE GAS and is one of the main causes for global warming.

Using the internet as a resource, make up an information leaflet on Global Warming. You leaflet must include;

●What is global warming and what causes it.

●What damage it could do.

●What can be done to prevent it.

Corrosion – Not a Useful Reaction

Corrosion is a very destructive chemical reaction. It changes strong metals into weak metal compounds.

Rusting is the term we use when Iron metal rusts to make the compound iron oxide.

Why does iron rust?

Look at the picture below. Why has the iron nail in the first test tube become rusty while the other two have not?

Take the Spotlight Science 2 text book and turn to page 78 – Rusting Parts.

Read this page and answer questions (a)-(g) in the space below.

______

Teachers checkpoint

“What can we learn about corrosion from the above picture?”

Prevention of Rusting: Barrier Protection

Metals have a great many uses but the main problem with using metals is that they will corrode if we do not find ways to protect them.

Internet/research task

Using the Internet prepare a power point on ways to protect metals from corroding.

Teachers checkpoint

7. Speed of Reactions

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In this section of the course we will have a closer look at what happens during a chemical reaction and how we can change the speed of a chemical reaction.

Your teacher will now show you DVD(1) – Rates of Reaction

Some chemical reactions go faster than others. An explosion is and extremely fast reaction, making toast is a reasonably fast reaction and rusting of a car is a slow reaction.

How Fast?

Look at the box below. Discuss the speed of each reaction with your partner and complete the table by ticking the correct boxes.

Chemical Reaction / Reaction Speed
Slow / Medium / Fast
Petrol exploding
A gate rusting
Wood burning
A Firework going off
Baking bread
Fermentation
Striking a match
Finger nails growing
Teachers checkpoint

Collision Theory of Reacting Particles

For any reaction to occur the reactants must be in contact. They must be in contact to allow their atoms to collide and form new substances. This is called Collision Theory. Anything that is done in a reaction to help particles/atoms to collide together will speed it up.

Can you think of some ways you could speed up a chemical reaction?

______

Your teacher will show you more about collision theory using multimedia science school. Note down your findings.

Findings: ______

We will now further investigate 3 factors which can affect the speed of a reaction. Compare your experimental findings with the ones you have made using multimedia science school.

Particle Size of Solid Reactants

Think about the following:

(i)What cooks faster – potatoes or chips?

(ii)What burns faster – iron powder or an iron bar?

(iii)What reacts fastest – marble lumps or marble powder?

We will now investigate the last question!

Experiment 6 Reaction with Acid: Marble Lumps vs. Marble Powder

The next experiment involves reacting large and small sized lumps of marble chips with sulphuric acid.

Apparatus

From the trolley: 2 similar sized lumps of marble

1 bottle of dilute Sulphuric Acid

1 Piece of filter paper

Small measuring cylinder

From the cupboard: 2 narrow test tubes

1 Test tube rack

1 spatula

Safety goggles

Table of Results:

Experiment / What you observed
Marble lump + Acid
Marble powder + Acid

Instructions:

  1. Look at the table above, this is where you will write your results.
  2. Collect all the apparatus and chemicals you need
  3. Take one lump of marble and place it on the filter paper and carefully crush the lump into smaller particles using the spatula.
  4. Add 5cm3 of sulphuric acid to each test tube which are on a test tube rack.
  5. Then add the lump of marble to one test-tube and the powdered marble to the other.
  6. Note what you observe in your table.

Teachers checkpoint

Copy and complete the following questions: