1. L/O – To know how the pH scale can be used to show acids and alkalis

2. They all contain acids What do all these things have in common?
Which do you think is the most Acidic?
What would you need to find out?
They all contain acids

3. Universal Indicator can be used to test how strong an acid or an alkali is
Universal indicator changes colour in acids and alkalis
Strong acids = Red Weak Acids = Orange
Strong Alkalis = Purple Weak Alkalis = Light Blue
Neutral = Green
stronger acid
stronger alkali
strongacid
weakacid
weak alkali
strongalkali
neutral

4. pH
Colour in the squares the right colour and then stick in the examples (or you can write them in if you are short of time)

5. pH pH 1 – car battery acid pH 4 – lemon juice; vinegar
pH 6 – rain water; coke; citric acid
pH 7 – water; salt
pH 8 – washing up liquid
pH 12 – oven cleaner
pH 13 – sodium hydroxide; ammonium hydroxide

6. pH

7. Acid Or Alkali? Substance pH Description of acid/alkali soda water 6
Are the following substance acid or alkali?
Are they weak or strong (pH number)
Substance pH
Description of acid/alkali
soda water 6
car battery acid 1
soap 8
washing soda 10
stomach acid 2
oven cleaner 14
vinegar 4
very weak acid
very strong acid
very weak alkali
weak alkali
strong acid
very strong alkali
weak acid

8. Why is it important to know the pH of an alkali or acid?
Acids with a lower pH and Alkalis with a higher pH are more dangerous so precautions need to be taken such as eye protection etc
Less strong acids and alkalis are not as dangerous e.g. lemon juice