1. Neutralisation L.O: TO understand neutralisation reactions in terms of ions

2. 16/10/2015 Universal Indicator and the pH scale Strong acid Strong alkali Neutral Universal Indicator is a mixture of liquids that will produce a range of colours to show how strong the acid or alkali is: Stomach acid Lemon juice WaterSoapOven cleaner Baking powder An acid contains hydrogen ions, H + An alkali contains hydroxide ions, OH -

3. Making water into acids and alkalis Some compounds react with water to create acidic or alkaline solutions Alkalis, in aqueous solutions produce OH- (aq) hydroxide ions Acids, in aqueous solutions contain H+ (aq) hydrogen ions In the HCl gas fountain why does the water turn red with Universal indicator? The same thing can be done with ammonium hydroxide. What colour would the universal indicator turn? In neutralisation these ions react what do they form when put together? OH - (aq) + H + (aq) 

4. 16/10/2015 Neutralisation reactions When acids and alkalis react together they will NEUTRALISE each other: OH Na Sodium hydroxide Cl H Hydrochloric acid The sodium “replaces” the hydrogen from HCl Cl Na Sodium chloride H2OH2O Water General equation: H + (aq) + OH - (aq) H 2 O (l)

5. Match the reactants to their products hydrochloric acid + sodium hydroxide calcium nitrate + water hydrochloric acid + potassium hydroxide calcium chloride + water hydrochloric acid + calcium hydroxide sodium sulphate + water nitric acid + sodium hydroxide calcium sulphate + water nitric acid + potassium hydroxide sodium nitrate + water nitric acid + calcium hydroxide sodium chloride + water sulphuric acid + sodium hydroxide potassium nitrate + water sulphuric acid + potassium hydroxide potassium chloride + water sulphuric acid + calcium hydroxide potassium sulphate + water

6. 16/10/2015 Making salts Whenever an acid and alkali neutralise each other we are left with a salt, like a chloride or a sulphate. Complete the following table: Hydrochloric acid Sulphuric acidNitric acid Sodium hydroxide Sodium chloride + water Potassium hydroxide Potassium sulphate + water Calcium hydroxide Calcium nitrate + water

7. Your task is to find out what volume of acid is needed to neutralise your concentration of alkali  Set up your burette as your teacher has shown you  Add 10ml of your alkali using a pipette to a conical flask and add a few drops of universal indicator  Fill up your burette with your alkali  Slowly add the alkali swirling the conical flask as you go  Stop when your solution becomes neutral  Record the volume of acid needed

8. Class results Alkali concentration (mol / dm 3 ) Volume of acid to netralise (ml)

10. Conclusion  What is the pattern / trend  in terms of ions why does a higher concentration need less acid to neutralise (4 marks)  How accurate do you think the burettes are?  Are our results reproducible?