28/11/2018 Acids and Alkalis

Quiz on acids and alkalis 28/11/2018 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 _____

Hazard signs to learn… 28/11/2018 Acid Corrosive h i Harmful Irritant

Universal Indicator and the pH scale 28/11/2018 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

Neutralisation 28/11/2018 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

Useful acid-alkali reactions 28/11/2018 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