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Neutralisation

Neutralisation. The aim of this lesson is… To know what neutralisation is To be able to describe how pH changes in neutralisation To understand why neutralisation is useful and important. Indicator. Neutralisation. neutral. green. acid. alkali. blue. red.

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Neutralisation

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  1. Neutralisation The aim of this lesson is… To know what neutralisation is To be able to describe how pH changes in neutralisation To understand why neutralisation is useful and important

  2. Indicator Neutralisation neutral green acid alkali blue red • Universal _______ tells us what the pH of a solution is. • If the pH is below 7 we say it is an ___ and it will turn ___. • If it is above 7 it will turn ___ and we say it is an ____ . • If the solution turns ____ we say it is _____ and it has a pH of 7.

  3. Acid? Alkali? Neutral?Sort these words into three groups

  4. Big Picture • Gaviscon tv advert • http://www.gaviscon.co.uk/tv_adverts/index.php • What is the pH of the stomach contents? • What do you think the pH of the Gaviscon is? • What happens when the two combine? • Why are there lots of adverts for indigestion remedies on the TV around Christmas time??

  5. New Information • http://www.bbc.co.uk/learningzone/clips/neutralising-the-stomach/126.html

  6. Indigestion • Sometimes, hydrochloric acid can escape your stomach and burn your oesophagus (food pipe) • This is very painful but an indigestion tablet can relieve the pain

  7. Aim: to find out what happens when you mix acids and alkalis Method: • Add 25ml of acid to a conical flask • Add a few drops of Universal Indicator to the acid • Add 25ml of alkali to a different beaker • Add alkali to the acid drop by drop using a pipette whilst swirling gently and observe any colour changes Prediction: What do you think will happen and why? • Safety: • Finished experiment?? • Put your equipment away tidily • Draw a comic strip to show what you did for each step of the method • (don’t forget about how you kept yourself safe!)

  8. Conclusion and evaluation • What happened in your experiment? • Was your prediction correct? Why/why not? • How could you improve your experiment if you did this again? • Why do you think when an acid is reacted with an alkali this is called neutralisation?

  9. Neutralisation Acid + Alkali  Salt + Water acidic alkaline neutral neutral What is made?

  10. Use the pattern and the word equation to copy and complete these equations Nitric acid + Sodium Hydroxide  Sodium Nitrate + Water Sulphuric acid + Sodium Hydroxide  Sodium Sulphate + Water Hydrochloric Acid + Potassium Hydroxide  Potassium Chloride + Water • Hydrochloric acid + calcium hydroxide  ________ + water • Nitric acid + potassium hydroxide  ________ + water • _______ acid + potassium hydroxide  potassium sulphate + water • Sulphuric acid + magnesium _______  magnesium sulphate + ____ • _______ acid + rubidium hydroxide  rubidium chloride + water

  11. Use the pattern and the word equation to copy and complete these equations Nitric acid + Sodium Hydroxide  Sodium Nitrate + Water Sulphuric acid + Sodium Hydroxide  Sodium Sulphate + Water Hydrochloric Acid + Potassium Hydroxide  Potassium Chloride + Water • Hydrochloric acid + calcium hydroxide  ________ + water • Nitric acid + potassium hydroxide  ________ + water • _______ acid + potassium hydroxide  potassium sulphate + water • Sulphuric acid + magnesium _______  magnesium sulphate + ____ • _______ acid + rubidium hydroxide  rubidium chloride + water

  12. Equipment 100 cm3 beaker hydrochloric acid samples of antacids spatula 50 cm3 measuring cylinder Universal Indicator solution balance stirring rod How could you investigate which indigestion tablet works best? How will you make sure your experiment is a fair test? Which is the best antacid? Antacid is another word for indigestion remedy!

  13. Possible extra investigation Aim: to investigate which is the best antacid Method • Add Universal Indicator to 40ml of acid • Measure out 10 g of an antacid • Add one spatulaful of antacid to the acid and stir until it is neutralised. • Measure the amount of antacid you have left, and work out how much you have used. • Repeat the experiment using different antacids.

  14. Possible extra investigation Conclusion • Which antacid was best at using up the acid? • How did you decide which the best antacid was? • Why is the amount of acid the antacid removes important? • How could you find out which antacid works the most quickly?

  15. Extension • How could you investigate how fast an indigestion tablet worked? • Design an experiment to investigate this

  16. Review 1:Any other uses of neutralisation? • Wasp stings are treated with vinegar • Bee stings are treated with bicarbonate of soda • What does this tell us about the pH of the bee and wasp stings?

  17. Review 2: Importance of neutralisation • An ant has stung Roxanne. • Alexander tells her that ant sting is formic acid. • How could Roxanne treat her sting? • Explain how your treatment would work

  18. Review 3 • http://sv.berkeley.edu/showcase/flash/juicebar.html • Challenge 3 looks at changing the pH but with a red cabbage indicator

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