Materials 1.4 Acids and Alkalis
Sc3: Materials and their
Properties
1.4 Acids & Alkalis
P.O.S.
Key Stage 3: 3d, 3e, 3f
Materials 1.4 Acids and Alkalis
LEARNING OBJECTIVES
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To recognise that acids have a sour taste (SAFETY SYMBOL)
To be aware that many everyday chemicals and foods contain acids
To understand that acids can burn you and can be dangerous
To know that we must wear goggles when using acids
To recognise common hazard symbols associated with acids
To observe the colour changes that occur when acids are added to certain plant dyes
To observe the effect of acids on bicarbonate of soda
To use litmus paper as a more sophisticated method of detecting an acid
To use the term “indicator” when describing an acid
To recognise that there are some substances that are not acids
To recall that the opposite to an acid is an alkali
To understand that a substance that is neither acidic nor alkaline is called neutral
To know that tap water is (more or less) neutral
To know that we can make an acid neutral if we add an alkali
To understand that we can use neutralisation to treat bee stings, wasp stings and indigestion.
Materials 1.4 Acids and Alkalis
ICT
LINKS
VOCABULARY
Internet research
Food Technology
Acid, alkali, sour, burn, goggles, fruit, indicator,
litmus, red, blue, neutral, neutralise, bee sting, wasp
sting, stomach acid, corrosive, harmful
ACTIVITIES
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Tasting various acidic substances e.g. citrus fruits, acid drops, vinegar
Create an exhibition of all the foods that contain acids
Look at the labels of chemicals like limescale remover to consider the hazard symbols which
represent corrosive and harmful
Making plant dye extracts using beetroot and red cabbage. These can be used in liquid form
(store in freezer) or soaked into filter paper to make an indicator paper when dry.
Testing red cabbage and beetroot juice with common acids like vinegar and lemon juice to
observe the associated colour changes.
Using sodium bicarbonate powder to test for acids in liquids. Drip liquid onto the powder,
bubbles of gas indicate that the liquid contains an acid. Acids will turn litmus red.
Using neutral litmus paper to test a range of everyday liquids including water and some alkalis.
Litmus will turn blue in an alkali and will stay the same colour in a neutral solution.
Making a model bee sting with a test tube of acid. Add small quantities of sodium bicarbonate
until the fizzing stops. Test the resulting solution to show that it is no longer an acid – hence no
more sting. Wasp stings are alkaline in nature; we treat these with vinegar, an acid.
Testing indigestion tablet to show that they contain alkalis.
Adding indigestion tablet to a model stomach full of acid (test tube). The tablets will effervesce
and neutralise the acid.
Making a poster of common substances, acidic, alkaline and neutral.
Use universal indicator to test soils for acidity/alkalinity
RESOURCES
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Lemons, limes,
oranges,
grapefruits, vinegar,
lemon juice
Sour tasting sweets
e.g. old fashioned
acid drops,
“refreshers”
Vinegar, lemon
juice, pickled
onions, apples
Limescale remover
(empty bottle only
Beetroot, red
cabbage, chopping
board, knife, pans,
cooker or Pyrex
beakers and
bunsen/tripod/
gauze
Pestles and mortars
or food blender,
filter paper or
access to fridge
Sodium bicarbonate
powder
Spotting tiles
Spatulas
Dropping pipettes
Litmus paper (blue
and red, or neutral)
Solutions of
POINTS TO NOTE
Materials 1.4 Acids and Alkalis
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everyday acids as
before
Everyday alkalis
e.g. soap solution,
washing powder
solution, Calgon
(sodium carbonate)
solution, sodium
bicarbonate soultion
Test tubes
Paper, pens to
make posters
OWN ACTIVITIES
POSSIBLE INVESTIGATIONS
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Which fruits/vegetables contain acid? Test with bicarbonate of soda or litmus paper.
For more able pupils: Which fruits contain the strongest acids? Taking equal quantities of fruit juices in test tubes, add measured quantities of sodium
bicarbonate powder until the fizzing stops. The stronger the acid, the more bicarbonate that needs to be added.
Which is the best indigestion cure?
Materials 1.4 Acids and Alkalis
Name:
Date Record Began:
Outcomes: NC Level 1  NC Level 4
1
1+
2
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3
3+
4
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Has tasted foods containing acids
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Knows that acids can be dangerous
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Can describe acids as having a sour taste
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Can name a food that contains acid
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Knows that acids can burn you
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Understands the appropriate safety precautions to take when using acids e.g.
goggles, wash off splashes etc
Can describe the colour changes that occur when acids are added to plant dyes
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Recognises that using bicarbonate of soda is a method of testing for acids
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Recognises the safety symbols for corrosive and harmful
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Understands that using indicators like litmus is reliable method of testing for acids
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Knows that litmus is an indicator which will turn red in an acid
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Recognises that there are some substances which are not acids
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Understands that litmus will turn red in an acid and blue in an alkali
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Knows that we can treat a bee sting with sodium bicarbonate
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Knows that we can treat acid indigestion with tablets which will get rid of some of
the acid
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Knows that litmus will not change colour in a neutral solution
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Knows that the opposite to an acid is called an alkali
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Understands that a substance that is neither acidic nor alkaline is called neutral
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Know that tap water is more or less neutral
Further Comments