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.

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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 an 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. Acids and Alkalis – The pH Scale

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im In this part of the topic you will learn about acids, alkalis and neutral substances and how they can be identified using the pH scale.

Think/Discuss

Have you heard of acids and alkalis before?Do you know any examples of acids and alkalis?

Ask your teacher to show the DVD(3) on Acids and Alkalis

2.1 Acids and Alkalis

There are many different chemicals in the world – so many that it is impossible to study them all. To make things easier scientists have put chemicals into different groups. Acids and alkalis are two of theses chemical groups. Acids and alkalis are chemical opposites.

The pH ScaleThe pH scale is a numerical scale which goes from 1 to 14 and tells us whether a substance is an acid, an alkali or neutral. You will find acids, alkalis and neutral solutions in a laboratory but we also come across them in our everyday lives.You will also notice that the numbers have an associated colour.

The pH scale

The rules for using the pH scale are:

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1413121110987654321

Acid Alkali Neutral

Using the pH scale handout make your own pH scale and stick it in the space below.

Make sure you have a heading and complete the following paragraph:

The numbers on the pH scale range from ___ to ____. The pH of a substance tells us how ac_ _ _ _ or al _ _ _ _ _ _.A substance with a pH 9 is an a _ _ _ _ _. A substance with a pH of 7 is n_ _ _ _ _ _. A substance with a pH of 14 is an a _ _ _.

Teachers checkpoint

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● Acids have a pH of less than 7.

● Alkalis have a pH of more than 7.

● Solutions with a pH of exactly 7 are called neutral.

2. Making an indicator from beetroot

im: In this section you will use cabbage to make an indicator.

Read: Chemists use indicators to tell if a substance is acidic, alkaline or neutral. Usually a chemical called Universal Indicator is used but we can also use everyday items like cabbage and beetroot.Follow these instructions to make your own indicator:

Wear gloves when preparing the indicator solution to avoid staining your hands. This method uses about ¼ of a beetroo

1. Chop the piece of beetroot into 1-inch pieces and place in a beaker.

2. Add 50cm3 hot distilled water from a kettle until the dye is removed from the beetroot.

3. Decant into a clean container. Keep the liquid, discard the beetroot.

4. Allow the indicator solution to cool before using.

Now we can add the indicator to different substances and observe the colour change. In the table below fill in the result as you complete the experiments.

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Step 1: Collect three test-tubes and a test-tube rack.Step 2: To each test-tube add approximately 10cm3 of

solution A, B and C.Step 3: Using a dropper add in 4 drops of your beetroot

indicator and note down the colour change.

im Our aim at this point is to learn through experiment how we can test different substances to see if they are acid, alkali or

Solution Starting Colour Finishing Colour

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3. Measuring pH

neutral. We will be using the pH scale and chemicals called indicators.

3.1 pH Indicators

To measure pH we must use a chemical called a pH indicator. When the indicator comes into contact with an acid, alkali or neutral substance it will change colour. This colour can then be matched to the pH chart to work out the pH number of the substance.

There are several types of indicators:

● Special paper called pH paper● A chemical called universal indicator● An electronic pH meter

Note: To measure the pH of a solid we must dissolve it in water first!

Experiment 2: Measuring the pH of different substances

Your teacher will demonstrate how to use universal indicator/ pH paper and a colour chart to measure the pH of some liquids and some solid substances.

While your teacher is setting up write the heading ‘Testing the pH of Household Items’ and copy the following results table into your jotter.

Substance pH Acid/Alkali/NeutralVinegar

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LemonadeSoda waterHousehold cleanerTable saltIndigestion tabletsSugarWashing powderOrange juiceDistilled waterMouth wash

Follow the instructions given by the teacher.

Teacher checkpoint

Once you have had your work checked by your teacher, complete the following paragraph

pH paper, a pH meter or U_ _ _ _ _ _ _ _ I_ _ _ _ _ _ _ _ can all be used to measure pH. If we had to measure the pH of a solid we would have to d_ _ _ _ _ _ _ it in water first.

1. Collect your own pH colour chart and some colouring in pencils. Colour it in and paste it into your jotter.

2. Louise measured the pH of several solutions using universal indicator and wrote down her results in a table.Solution Colour pH

A Purple 13B red 2C blue 10D Orange 4E green 7

(a) Which solutions are acids?

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(b) Which solutions are alkalis?(c) Which solution is neutral?(d) Which solution is most acidic?(e) Which solution is most alkaline?

3. Copy and complete the following:

Acids often turn universal indicator R_____ or O_______ and have a pH number of 1 to __. Alkalis often turn universal indicator P_______ or B___________ and have a pH number of 14 to ___. Neutral solutions like pure water will turn universal indicator __________ and have a pH number of _

Teacher checkpoint

im In this section we will look at what happens to the pH of strong acids and strong alkalis as they are successively diluted.

3.1 Dilution of Solutions

In first year, during the Model of Matter course, you learned how to change a concentrated solution into a dilute solution. Can you remember what you had to add to do this?

Experiment 3: Dilution of a Strong Acid and a Strong Alkali

Write a heading in your notes and copy the following results tables into your jotter.

Acids Colour of pH paper pH of SolutionAcid Solution AAcid Solution B

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4. Dilution of Acids and Alkalis

Acid Solution C

Alkalis Colour of pH paper pH of SolutionAlkali Solution AAlkali Solution BAlkali Solution C

Apparatus: Acid solution A Alkali solution A Two Large glass beakers pH paper Large measuring cylinder Small measuring cylinder Stirring rod Safety glassesInstructions:

1. Measure out 5ml of Acid solution ‘A’ and measure the pH off the solution using some pH paper. Record you results in your table.

2. You will now make solution B. Pour the 5ml of acid solution A into the large beaker. Add 200ml of water to the beaker and mix the solution. Measure the pH of acid solution B again using pH paper. Keep solution B. Record your results.

3. You will now make acid solution C.This time pour the 5ml of acid solution B into the large beaker. Add 200ml of water to the beaker and mix the solution. Measure the pH of solution B again using pH paper. Record your results.

Teacher checkpoint

4. Wash out all your equipment with water when you have finished.

5. To find out the results for diluting an alkali repeat the above instruction only this time start with Alkali

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Solution A. Again record all your results in your table.

6. Once you have completed the experiment tidy up, wash all your apparatus and put it away.

Teacher checkpoint

Complete the following paragraph by filling in the blanks:

Acids with a pH of _ are the most acidic. Alkalis with a pH of _ _ are the most alkaline. When w_ _ _ _ is added to an acid the pH will i _ _ _ _ _ _ _ towards 7. When w_ _ _ _ is added to an alkali the pH will d _ _ _ _ _ _ _ towards 7.

Draw a diagram to show how an acid is diluted, remember to show the colours of the universal indicator as the acid changes.

Teacher checkpoint

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5. Neutralisation

im In this section we will look at what happens when we mix acids and alkalis together. The reaction that occurs is called Neutralisation.

ReadLook back to the pH chart. Find the pH number of a solution which is neither acidic nor alkaline. What colour would this go in universal indicator? What is the pH number of this solution?Remember, solutions which are neither acids nor alkalis are called neutral solutions.

You can make a neutral solution by adding an acid to an alkali together.

Copy and complete the equation above and collect a copy of the diagram below. Use coloured pencils to colour the solutions in the beaker. Use the pH chart to guide you.

Teacher checkpoint

In every neutralisation reaction between an acid an alkali the neutral substances made are a salt and water. When Hydrochloric acid reacts with the alkali sodium hydroxide the products are water and a salt called sodium chloride.

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ACID + ALKALI → _________ SOLUTION

Questions:N_ _ _ _ _ _ substances are formed by a neutralisation reaction. The pH of these substances is _.

Teacher checkpoint

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6. Everyday Neutralisation Reactions

im: In this section you will learn why neutralisation reactions are useful in everyday life.

Read Neutralisation reactions are used to neutralise acids in many everyday life situations.

Many gardeners will have bags of a powder called lime in their garden sheds. If the soil in their garden is too acidic, they will sprinkle the lime onto the soil. Lime is an alkali so it will neutralise the acid in

the soil. This will help the plants grow.

Due to acid rain, many lakes in Sweden are turning acidic. This is killing the fish. Lime powder is sprinkled from aeroplanes onto these lakes to neutralise the acid and help save the fish.

You will probably have heard people complaining of having indigestion. This is often caused because there is too much acid in the stomach. To neutralise the acid people take indigestion remedies. An example of an indigestion remedy is milk

of magnesia. Milk of magnesia is an alkali so it neutralises the acid in the stomach and stops the pain.

Have you ever been stung by a bee or a wasp? If you do get stung it pays to remember

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milk of magnesia

some neutralisation chemistry! A bee has an acidic sting. If you want to help stop the pain you should neutralise the sting by putting an alkali onto it. Many people put the household alkali called baking soda onto bee stings because baking soda is an alkali and it neutralises the acid in the bee sting.

Wasp stings are different from bee stings. Wasp stings are made from an alkaline substance so to neutralise a wasp sting we need to add an acid. Many people put vinegar onto a wasp sting. Vinegar is an acid and so it will neutralise the alkali in the wasp sting and help stop the pain.

Complete the following sentences by filling in the blanks.

L _ _ _ _ will neutralise acid in soil. Sweden uses thousands of tonnes of lime every year in order to stop the a_ _ _ r _ _ _ _ from killing the fish.

Indigestion is caused by too much a _ _ _ _ in the stomach. Milk of magnesia is used to neutralise this acid.

B _ _ _ _ _ S _ _ _ is used on a bee sting to neutralise the acid in the sting.

V_ _ _ _ _ _ is used to stop the pain of a wasp sting. This works because the v_ _ _ _ _ _ neutralises the alkali in the wasps’ sting.

Teachers checkpoint

Internet Research

ACID RAINACID RAIN15

You have just read a section which mentioned one of the problems of Acid Rain. Your next task is to research the problem of Acid Rain and prepare a power point presentation or an information leaflet or a scientific poster on this problem. You can use the internet as a resource, or any books the Science Department may have.

Your presentation must include:

● The causes of Acid Rain● The effects on animals, plants and buildings● How we can solve the problem of Acid Rain.

Teacher checkpoint

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7. Neutralisation Investigation

im: In this section you will carry out an investigation to find out which fast food shop has diluted their vinegar.

In your group, discuss how you could use the apparatus to do the experiment (see list below). At the end you must be able to say if any of the bottles of vinegar have been watered down.What volume of vinegar will you start with?If you decide to use an indicator, which one will you use? How can you find out what colour change you will see?Think about how you are going to record your results.Good chemists will repeat their experiments. Why?

We need to know when all the vinegar we have started the experiment with has been neutralised. This is where we can use special dyes called indicators. They change colour when the neutralisation is complete. How will you know what the colour change of the indicator will be? How will you be able to tell if any of the bottles of vinegar has been watered down?

Apparatus: Measuring cylinders Small beakers Plastic dropping pipettes and syringes Two test tubes in a test tube rack

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Stirring rods Bottles of indicator solutions Bottles of dilute sodium hydroxide solution White tiles

You also have:A bottle of vinegar from the supermarketBottles of vinegar from each of the three Fast Food shops

Record your ideas (you can use diagrams too) on the Experiment 1 Notes Sheet and then get it checked.

Once your teacher has checked your plan you should carry out your investigations in groups.

You should then complete the report sheet with the help of your group.

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8.Fertilisers and Neutralisation Reactions

im: In this section you will learn why fertilisers are important and about some of their properties.

ReadPlants take in the elements that they need for growth from the soil, without these elements they would are not able to grow properly. When plants are harvested some of the elements that the plants need are removed. In order to replace these nutrients fertilisers are added. Fertilisers are made by neutralisation reactions.You have already learned that adding an acid to an alkali produces a salt and water:

Acid + Alkali → Salt + Water

Depending on the type of acid and alkali used the salt produced can be used as a fertiliser.

Here are some examples:

Nitric + Potassium → Potassium + water acid Hydroxide Nitrate

ammonia + nitric acid → ammonium nitrate + water

phosphoric acid + ammonia → ammonium phosphate + water

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9 Essential Elements

im: In this section you will learn the names of the three elements that are always used in fertilisers.

ReadYou already know that we can help keep plants healthy by using chemicals to kill pests, diseases and weeds but unless plants get the correct food they will still not be able to grow healthily.

You will already know that some things are essential for animals to stay alive. It is the same for plants. There are three elements in the periodic table that plants must have to survive. These elements are called essential elements because the plant would die without them.

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Sarah carried out an experiment to find out the names of these three essential elements and wrote a conclusion in her jotter.

Use a periodic table and

the picture of Sarah’s jotter above to copy and complete the following sentence.

10. What is a fertiliser?

imIn this lesson, we will learn about fertilisers and why they are important in the production of food.

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Conclusion: the three essential elements that plants need have the symbols:N, P and K.

The three essential elements that plants need to grow are ______________________, _____________________ and __________________.

Think about where you have heard about fertilisers before, share your ideas with your partner. Your teacher will then ask for your ideas.

Watch as your teacher shows you a power point presentation / video on the importance of fertilisers.

Write down three key facts on why fertilisers are important.

ReadThe population of the world is steadily getting bigger. This means that we need to make more food to feed more

people. To make more food, farmers need to make their crops grow bigger and faster. They give their crops extra help by giving them plant food. The scientific word for a plant food is fertiliser. The chemical industry has found ways to manufacture fertilisers for farmers to meet the world demand for

more food.There are two main kinds of fertilisers. The ones that are made by the chemical industry are called artificial fertilisers. There are four major types of articicial fertilisers: ammonium, nitrate, phosphate and potassium.

Ferlisers that are made from living things are called natural fertlisers. Manure and compost are examples of natural fertilisers.

Using the information above answer the following questions:

1. Fertilisers that are made from chemicals are called artificial fertilisers and fertilisers that come from living things are called n _ _ _ _ _ _ fertilisers.

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2. Complete the table below.

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Name of artificial fertilisers

Names of natural fertilisers

11. Which fertiliser in best?

Alex carried out an experiment to compare how effective different brands of artificial fertilisers are. The steps he did in the experiment are shown below.

Dissolve the solid fertliser in some water.

Add some of the dissolved fertiliser to the plant pot.

Check the plants after two weeks but remember to water them.

His results are shown in the table below.

1)Complete the table of Alex’s results, use the sums written in brackets to help you.2)Collect a half sheet of graph paper and draw a graph to show the growth of the plants for each brand of fertiliser.3)Which fertiliser was the best?________________________4)Which fertiliser was the worst?_______________________5) Why did Alex dissolve the solid fertiliser first?_____________________________________________________________

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Brand of fertiliser

height of plant at start (cm)

height of plant after two weeks(cm)

growth of plant (cm)

Hi-grow 13 19 (19-13=?)Green-up (16 – 5=?) 16 5Mo-green 12 (12-3=?) 3Wondaplant (9-4=?) 9 4

_________________________________________________________________________________

11 Fertilisers and Solubility

imIn this lesson you will investigate the solubility of fertilisers.

ReadYou already know that fertilisers must be in solution before the plant can take them into their roots. This means that a fertliser must be a soluble compound.

Experiment 5:Complete the following sentence.1. I am going to test S_______ of some fertilisers.2. Complete the table below.

Follow the instrucions on the sheet, fill in your table as you go along then answer the questions below.

3. Describe how you carried out the experiment in the space below:

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Name of compound soluble or insolubleAmmonium sulphateSodium nitrateCalcium phosphateAmmonium phosphatePotassium nitrate

a) In the space below, write down how you knew a compound was soluble or insoluble.

4. In the space below, write down the names of the soluble componds.

____________, ______________, _________________

____________.5. Could the compounds that you have written above be used as a fertiliser?

6. In the space below write the name of the compound that could not be used as a fertiliser

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12 Problems with fertilisers

im: In this section you will learn about the effects that fertilisers can have on the environment.

ReadYou have learned already that fertilisers need to be soluble for a plant to take them into their roots. Fertilisers made from nitrate compunds are very soluble and this can cause pollution problems.

If the farmer uses too much fertliser or if there is a lot of rain the extra fertiliser can be washed into rivers and streams. This means that the levels of nitrates in rivers, streams and lochs increases.

High levels of nitrate fertilisers in rivers can kill fish and other water life and leave the water lifeless.

The nitrate fertlisers can also get into the public water supply which can be dangerous to health.

Complete the paragraph below.Nitrate fertilisers will be washed into the r_ _ _ _ _ if a farmer uses too much or there is too much rain. This

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fertilisersRivers and streams

i_ _ _ _ _ _ _ _ the levels of nitrates in the river and can k _ _ _ f _ _ _ and leave the water lifeless. Nitrates can also get into the public water supply and can be d_ _ _ _ _ _ _ _ to health.

Extension / Homework task

Design a scientific poster or leaflet about the benefits and dangers of using fertilisers in our world today.

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13 Fertilisers Investigation

im: In this section you will be able to test some fertilisers for the presence of the three essential elements ( ammonium, phosphorus and potassium)

Complete the table as you finish each experiment.

Experiment 6:

Collect experiment card 3.20.1 and carry out the experiments then try the work below.Use the table below to check if the ions are present.

Fertiliser Ion

Experiment Result if ion is present

Ammonium Turns pH paper blue/purplePotassium Burns with a lilac flamePhosphate Turns the solution into a yellow solid

1. In the space below, write down how you tested the ammonium compound.

_________________________________________________

2. In the space below, write down how you tested the potassium compound.

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Fertiliser ammonium yes or no

potassium yes or no

phosphate yes or no

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____________________________________________

2. In the space below, write down how you tested the phosphate compound.

___________________________________________

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