BASIC FACTS ABOUT ACIDS AND ALKALIS

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Ivan

1. 24/02/11 1
TELLING THEM APART
ACIDS
&
ALKALIS
Chapter One

2. What are Acids?
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YOUR TASK
Write down all you know about
Acids.

3. 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.

4. 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.

5. 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.

6. 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

7. 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?

8. 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

9. FACTS ABOUT ACIDS
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•Acids are generally dangerous
chemicals.
•Acid compounds all contain hydrogen.
•They dissolve in water to produce
particles called hydrogen ions.
•Never drink them or put them near
your eyes.
•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.

11. 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.

14. 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 BASES
Starter Activity
What are Acids and Bases?
Name a few examples.

16. 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.

22. 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.