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TELLING THEM APART

ACIDS&

ALKALIS

Chapter One

What are Acids?

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YOUR TASKWrite down all you know about

Acids.

PROPERTIES OF ACIDS

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1.Acids have a sour taste.2.Acids turn litmus solution red and turn

blue litmus paper red. 3.Acids have pH numbers less than 7 that

is pH 1-6.

PROPERTIES OF ACIDS

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1.Acids have pH numbers less than 7 that is pH 1-6.

2.The lower the pH the stronger the Acid.3.The higher the pH the weaker the Acid.

Strong And Weak Acids

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An Acid is classified as strong or weak depending on its ability to dissociate in water.

Acids dissociates when the turn from molecule into ions when dissolved in water.

Strong Or Weak Acid

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A strong Acid dissociates completely in water. E.g Sulphuric Acid or Nitric Acid

A weak Acid dissociates partially in water e.g Ethanoic Acid

YOUR TASK

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Acids have many properties that distinguish them from other

substances.

Can you write down some of these Can you write down some of these properties?properties?

PROPERTIES OF ACIDS

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1. Acids have a sour taste.2. Acids turn litmus solution red and turn blue

litmus paper red. 3. Acids have pH numbers less than 7 4. Acids react with metals, forming hydrogen

and a salt 5. Acids react with carbonates, forming a salt,

water and carbon dioxide 6. Acids react with alkalis, forming a salt and

water 7. Acids react with metal oxides, forming salt

and water

FACTS ABOUT ACIDS

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1. Acids are generally dangerous chemicals.

2. Acid compounds all contain hydrogen.

3. They dissolve in water to produce particles called hydrogen ions.

4. Never drink them or put them near your eyes.

5. Never pour water into a concentrated acid as it heats up and can spit hot acid at you.

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How do scientists test for acids and basic solutions?

Scientist can test a substance to see whether

it is acidic or basic (alkalis) by using an

indicator.

INDICATORS

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What are indicators?

Indicators are substances that will change colors when they come in contact with an

acid or a base.

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Why do we need indicators?

Indicators are a safe way

to help scientist determine whether a substance is an

acid or an alkali.

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Remember what we said about acids and alkalis. Often you do not

want to come in direct contact with them as they can be harmful.

WARNING

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Never pour water into a concentrated acid as it

heats up and can spit hot acid at you.

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ACIDS AND BASESStarter Activity

What are Acids and Bases? Name a few

examples.

FACT

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Acids and bases are two important classes of

compounds that have different properties from one another.

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ACIDS-often give food a sour, sharp flavor (lemon juice) and

can be helpful, such as the acids in your stomach. Strong

acids can burn your skin.

BASES- on the other hand feel bitter and slippery.

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The following table shows colour changes and changes range for 4 indicators

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INDICATORS TYPES AND USES LEARNING OBJECTIVES

•To understand what indicators are and why scientist use indicators•To know the different indicators and how they are used to test for acids and alkalis•To understand how to read pH scale and interpret the pH scale

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ACIDS

Acids are materials that have certain properties in

common.

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BASES

Bases (also called alkalis) are other substances with

a different set of properties.

FACT YOU SHOULD KNOW

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The most striking property of both acids and bases is their ability to change the colour of certain vegetable

materials.