Post on 23-Feb-2016
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7E ACIDS AND ALKALIS
The pH scale• What is the pH scale?
• What pH does an acid have?
• What pH does an alkali have?
• What is the neutral pH
The pH ScaleA way to measure how acidic or alkaline a
substance is
Universal indicator paper shows a different colour for each pH
Indicators
• What is an indicator?
• Which indicator has many different colours?
• Name some other indicators.
Acids and alkalis in the Science lab
• Which hazard symbols might acids or alkalis have?
• What should you do if you get acid or alkali on your skin? Why?
• Name two acids and two alkalis you might use in the science lab.
The power of acids
• http://youtu.be/kcDSngXldB0• http://youtu.be/F5jfRjzXLbE
• Looking at acids and alkalis in the lab
Acids and alkalis in the lab
More acids and alkalis
• Card sort
Indicators
• What is an indicator?
• Name 3 indicators.
Things to do:1. Write a method for the experiment2. Do a diagram of the experiment3. Make your indicator and write about it is the table
Colour in acid Name of indicator Colour in alkali
Acid rain
• What is acid rain?
• Which gases cause acid rain?
Next
• Draw a diagram to show how acid rain is formed
Answer the questions
• Do you think that the acid rain problem in the UK is over or not? Explain your answer with evidence from your work.
• How can countries try to solve the acid rain problem?
Neutralisation
• What is neutralisation?
• Complete this formulaAcid + Alkali →
• Name 3 examples of when neutralisation is useful.
NeutralisationPut 8cm3 of alkali in a test tubeAdd 1 cm3 of acid, stir and remove a drop of liquidTest the pHWash the dropperAdd 1 cm3 more of acid
Volume of acid (cm3) pH
0
1
2
3
4
5
…
Your task is to design a page in a family health book all about insect
stings and how to treat them.
Step 1
Find out the pH of wasp and bee stings.
Insect sting
Colour with universal indicator
pH
Wasp
Bee
Step 2
To get rid of an insect sting you need to neutralise it. What pH will neutralise the:
a) Wasp sting?
b) Bee sting?
Step 3
Find out the pH of these household chemicals.
Chemical Colour with universal indicator
pH
Vinegar
Water
Bicarbonate of soda
Step 4
Which chemical would you use to treat the:
a) Wasp sting?
b) Bee sting?
Step 5
Design your book page on plain A4 paper. Try to find out this extra info: What are the chemicals in wasp and bee stings?