1. W Richards Worthing High School
20/05/2019
Acids and Alkalis
W Richards
Worthing High School

2. Quiz on acids and alkalis
20/05/2019
Acid, alkali or both???
This a pH of less than 7
This could kill cells
This is often used in cleaners or soap
This would turn Universal Indicator red
Sodium hydroxide is a common ____________
This would feel soapy on your skin
This could be a corrosive
This will turn universal indicator purple
This would taste sour
Lemon juice and vinegar are examples of weak _____

3. Hazard signs to learn…
20/05/2019
Acid
Corrosive h i
Harmful
Irritant

4. Universal Indicator and the pH scale
20/05/2019
Universal Indicator is a mixture of liquids that will produce a range of colours to show how strong the acid or alkali is: 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Stomach acid
Lemon juice
Water
Soap
Baking powder
Oven cleaner
Strong alkali
Strong acid
Neutral

5. Neutralisation
20/05/2019
An acid and alkali will neutralise each other (if the correct amounts are used:
Acid + alkali Salt + water
E.g. hydrochloric acid + sodium hydroxide sodium chloride + water

6. Useful acid-alkali reactions
20/05/2019
1) Hydrochloric acid is used in the stomach to help _______. If we eat too many “rich” foods our stomachs create too much ____ – this is called ______. This acid needs to be neutralised by taking indigestion tablets.
2) Soil is naturally acidic, mainly due to acid ____. This can have bad effects on ____ and vegetable growth, so the excess acid may need to be neutralised with an _____ or suitable fertiliser.
Words – plant, digestion, indigestion, alkali, rain, acid