Antacid Acid Experiment

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Aim: To use cabbage as an indicator for whether lemon juice, soft drink and antacid are acids or bases.
Hypothesis: The lemon juice will be a reasonably strong acid but not so much that it can burn your tongue if consumed. The soft drink will be a weak acid, it is not as acidic as lemon and is safe to drink. I think antacid will be an acid.
An indicator is used to determine the position of a substance on the pH scale. In this experiment, red cabbage is used because it contains a pigment molecule known as flavin. This means that it changes colours depending on the quantity of hydrogen ions in the solution. The red cabbage can produce red, purple or blue juice. The colour it produces depends on the pH of the water it has been mixed with.
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Some have the ability to burn other materials. Usually they are sour if eaten and will react with some metals. They also can conduct electricity. All acids can be neutralised by bases.
Bases are substances that release OH- (hydroxyl ions). They often have a soapy or slimy feel if touched and will taste bitter if consumed. Some can burn but generally not as strongly as acids can. All bases can be neutralised by acids.
When using red cabbage, the adding of acids causes the water to turn purples, pinks and reds (purples are weaker, reds stronger). The adding of bases causes it to turn blues, greens and yellows (blues are weaker, yellows stronger). The pH scale is a reliable way of determining the acidity of a substance that is dissolvable by water. A low score on the pH scale shows there are lots of hydrogen ions in the solution. A high score shows there are only a small amount. The score of 7 is considered to be neutral. In this case, there is an equal number of hydrogen and hydroxyl ions in the
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When the juice was added to the test tube it immediately turned the water a fluorescent pink. The colour was not light enough to be considered a 2 but it was not a dark pink either so we labelled it as a 3 on the pH scale. Lemon juice is considered to be a strong acid however it is still completely safe to touch and to consume.
The next solution tested was soft drink. After putting it into the test tube we noticed that it changed colour slower than the lemon juice. The water changed to a purple colour that we considered to be magenta. The colour wasn’t completely purple but it wasn’t pink either so it’s a 6 on the pH scale. Soft drink is a weak acid.
Finally we tested antacid. We dropped the tablet into the water and as it dissolved it slowly produced a turquoise colour. In the other test tubes the colour produced spread throughout the water however in this one the colour stayed in a small amount at the bottom of the test tube surrounding the tablet. This could be because the tablet was dissolving a lot slower than the other solutions so the colour moved slower as well. The turquoise colour fits between 8 (dark blue) and 10 (aqua) on the pH scale so we have found it to be a 9. Antacid is 2 above 7 on the pH scale, making it considered a weak

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