What is an acid?
Acids are a group of chemicals.
What do you know about acids? Are all acids dangerous?
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What is an acid?
Acids are a group of chemicals.
Which of these items contains an acid?
everyday acids
laboratory acids
Can you think of other examples of acids?
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What is a weak acid?
Acids are found in household items such as food, drink
and beauty/skincare products.
It is safe to handle these acids and even taste them, if they
are for eating! These acids are known weak acids.
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What is a strong acid?
Some acids, like those found in the laboratory or a car
battery, are very dangerous (too dangerous to taste or touch).
These acids are said to be corrosive as they can damage
other materials by wearing them away! They are strong acids.
Why must strong acids always be handled very carefully?
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What is an base?
bases are another group of chemicals, the opposite of acids.
Which of these items contains an base?
everyday bases
laboratory bases
Can you think of other examples of bases?
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What is a weak base?
bases are found in soaps and other materials used for
cleaning.
It is safe to handle these bases, which can feel soapy.
These bases are known as weak bases.
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What is a strong base?
Some bases, like those in the laboratory or in cleaning
materials such as toilet cleaner, are too dangerous to touch.
These bases are said to be caustic because they can burn
skin and damage other materials! They are strong bases.
Why must strong bases always be handled very carefully?
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What are hazard symbols?
How can you tell which chemicals are safe and which are
dangerous?
Special symbols are used on bottles and vehicles that
contain dangerous chemicals.
i
toxic
irritant
h
harmful corrosive
highly
flammable
These hazard symbols show why the chemical is dangerous.
Why is it important that these symbols can be recognised by
people from other countries?
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What is an indicator?
How can you test a liquid to find if it is an acid or an base?
An indicator is a special chemical that changes
to a different colour in an acid or an base.
Litmus paper and litmus solution are
examples of indicators.
Litmus is
red in acid.
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Litmus is
blue in base.
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What is universal indicator?
Litmus is used to show if a solution is acid or base.
Litmus does not show if the acid or base is weak or strong.
Universal indicator has a range of colours that show how
weak or strong the acid or base is.
stronger acid
strong
acid
stronger base
weak
weak
acid neutral base
strong
base
What is the colour for a weak acid?
What is the colour for a strong base?
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What is the pH scale?
The strength of an acid or base is measured by the pH scale.
Each universal indicator colour is given a number called
the pH value.
Universal indicator can tell you the pH of a solution.
stronger acid
stronger base
1 2 3 4 5 6
7 8 9 10 11 12 13 14
strong
acid
weak
weak
acid neutral base
strong
base
What is the pH of a weak acid?
What is the pH of strong base?
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What is the pH?
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What type of substance?
Are these substances acidic or basene?
Are they weak or strong?
Substance
soda water
car battery acid
1
Description of acid/base
very weak acid
very strong acid
soap
8
very weak base
washing soda
10
weak base
stomach acid
2
strong acid
oven cleaner
14
very strong base
vinegar
4
weak acid
acid
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pH
6
1 2 3 4 5 6
7
8 9 10 11 12 13 14
base
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Mixing an acid and an base
What happens when an acid and an base are mixed?
?
Mixing an acid and an base causes a chemical change.
This chemical change is called a chemical reaction.
How do you know this chemical reaction has taken place?
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What is neutralization?
The chemical reaction between an acid and an base
is called neutralization.
acid
base
a salt
water
What happens to the pH value of the reaction mixture during
neutralization?
The pH value of the reaction mixture becomes closer to 7.
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