2. Stomach Acid Remember in form 2 you learnt that your stomach normally produces acid to help with the digestion of food and to kill bacteria. The acid in our stomach is called hydrochloric acid. Hydrochloric acid has a pH of 1 or 2. When there is too much acid in our stomachs the acid may escape and irritate the oesophagus (gullet). This is called ‘acid reflux’ which can cause acid indigestion or heartburn. This is a very painful experience.

3. Scenario Mr Piper has ate too much spicy food, he is suffering from indigestion. He opens his medicine cabinet and sees two bottles containing tablets but there were no labels on the bottles. He panics because the pain is severe and he does not know which tablet to take and which one will give him a fast relief. As super scientist you need to discover which tablet will help Mr. Piper with his indigestion.

4. Stomach acid Spicy food Splashes Splashes of acid in oesophagus cause heartburn Mr Piper Stomach

5. Which Tablet is Best for Mr. Piper? Method 1. Crush each tablet up in a mortar and pestle 2. Weigh 5g of each tablet. 3. Put 25ml of hydrochloric acid in two small beakers 4. Add a few drops of universal indicator to the acid. What colour does it go?………………………… 5. Carefully tip each crushed tablet into the acid and stir it. 6. Look at the colour and put this in your table. 7. After 10 minutes look at the colour again and put it in your table. We are going to show the excess acid in his stomach, by pouring hydrochloric acid into a beaker.

6. TabletColour at 0 minutesColour after 10 minutes Tablet A Tablet B Results

7. Analysis For the tablet to have worked it has to neutralise the acid in the beaker. What colour is neutral with universal indicator?……………………………. Which of the tablets has got closest to this colour?……………………………………………………………………………. Conclusion Indigestion is………………………………………………………………………………………… From my results I conclude that the best tablet for Mr. Piper ‘s indigestion is………………………………………………………………………………….. I think this because…………………………………………………………………………… …………………………………………………………………………………………………………………

8. Consolidation We can cure indigestion by eating an alkali tablet such as Rennie or Gaviscon.

9. How does it work? The excess acid in our stomachs reacts with the alkali tablets. This causes a neutralisation reaction. When acids and alkalis are added together they neutralise one another. This causes the pH to get closer to 7.