My aim is to determine which tablet is the best for stomach acid (neutralises the most hydrochloric acid).
Acids and Alkalis
Many of the substances that we use today are made up of either acids or alkalis. These are two chemical opposites.
Most acids are liquids. They are very corrosive and can kill or burn skin cells, bacteria etc. Acids taste sharp and sour. Strong acids such as hydrochloric acid, sulphuric acid etc release hydrogen quickly whilst weaker acids such as citric acid and carbonic acid release hydrogen slowly. Strong acids measure at 1 or 2 on the pH scale and weak acids measure at 5 or 6 (The pH is a number on a scale which shows how acidic or alkaline a substance is).
Most pure alkalis are solid. Like acids they are also very corrosive. Most feel soapy but some can burn flesh. Strong acids measure 13 or 14 on the pH scale and weak acids measure 8 or 9.
Alkalis neutralise acids. At this point their pH level becomes 7 and they are known as neutral.
(acid + alkali ? neutral solution)
Hydrochloric acid/stomach acid
When your stomach wall makes too much hydrochloric acid you end up with a stomach-ache. Normally you are given an alkaline tablet to neutralise the acid.
Universal indicator can be in the form of paper or liquid. It is used to show whether something is neutralised or whether it is an acid or alkali. E.g. if the indicator goes red it is acidic.
Independent variables are the ones that I cannot keep at a certain amount e.g. Hydrochloric acid.
Dependent variables are the ones which I have to keep at a certain amount e.g. water.
My prediction is that whichever tablet neutralises the most hydrochloric acid is the best.
Firstly I will measure 30 ml of water in a measuring cylinder. Secondly I will put this water into a plastic beaker and dissolve a tablet into it. I will stir it with a stirring rod. After this I will add 7 drops of Universal indicator to the solution and stir it. I will put some Hydrochloric acid into a pipette and add it to the solution until it is neutral counting how many drops I add. Finally I will do this experiment twice for each tablet.
To make this test fair firstly I will make sure that I use the same amount of water and universal indicator. I will also dissolve the same amount of tablet each time. I will make sure that all the water used is all at the same temperature. Finally I shall do each experiment twice to ensure that I obtain accurate results.
Measuring Cylinder, Water, Thermometer, Plastic Beaker, Stirring Rod, Pipette, Hydrochloric acid,
Tablets – Gaviscon, Settlers, Tums, Calcium Carbonate
To make this experiment safe we should make sure we hold all chemicals and equipment with care as acids and alkalis, which are going to be used in this experiment, are corrosive. We should make sure all hair and scarves are tied properly so they do not get in the way. We should also wear goggles to protect our eyes.
First I measured and poured 25ml of sodium oxide into a plastic beaker. Then I added 7 drops of indicator until the solution turned pink. Then I measured 25ml of Hydrochloric acid and started adding this to the solution until it turned clear. This showed that the solution is neutral.
Table of Results
* Coloured / Flavoured Tablet
C.O.S. = Colour of Solution
Graph of Results
The above graph shows the average amount of drops of Hydrochloric acid added to neutralise a tablet.
After having analysed my results I have come to realise that Gaviscon is the best tablet to neutralise Hydrochloric acid.
(? Gaviscon + acid ? neutral)
I had predicted that whichever tablet neutralises the most hydrochloric acid is the best. I did not specify a certain tablet. This ties in with my prediction as it does neutralise the most. Tums was the next best then Settlers and finally Calcium Carbonate.
There are no anomalies in my work.
Accuracy and Reliability
I feel that I could have made my results more accurate by doing the experiment another time as I could have miscounted the drops. I think the reliability of my results is fair but improvements could have been made to make it a 100 per cent accurate.
Paying more attention to the different colours on the pH scale so that the overall pH number written could have been more accurate would have made improvements to the investigation.
Extending the Investigation
I could extend the investigation by using different types of water e.g. hot and cold. I could also have timed the experiment to see which tablet neutralises the fastest. I could also have tried using a wider range of tablets.