Chemistry Project Ideas
Showing Your True Color
When I was thinking of chemistry project ideas for this website, I cast my mind back to when I was at university. Many of the pracs involved chemical changes in acidity. Why is this – simply because there are so many reactions in chemistry, and in fact nature, that deal with acids and bases. To bring it closer to home, certain parts of your body work better at certain pH's. If you have the correct pH, you will feel healthy and strong because your body will work better. In a laboratory there are certain chemicals that are used to show changes in pH. These are called pH indicators. Nature has its own set of indicators! One of them is the hydranger flower. The flowers of this bush range in colours from pink/purple to blue (with various shades in-between) depending on the pH of the soil they are planted in. Hmmm – that in itself should give you some more chemistry project ideas. In this experiment we will make use of another natural indicator... Let’s do science...
The experiment
Aim
To demonstrate a change in pH using a natural indicator.
Equipment needed
White vinegar.Plastic bottle or other see through container.Two teaspoons of baking soda.Some leaves from a red cabbage.A pot.A stove or something you can cook on.A measuring cup.Some ice cubes.
Method
Take the cabbage leaves and put them in the pan, with some water. Put them on the stove and bring the water to the boil. The water should turn a pink colour. If it is not, put some more leaves in the pot and boil it again. (Get an adult to help out with this step.)Once you have a pot of nice pink water – remove the leaves and put some ice cubes in it to cool it – this is an optional step – you could just wait for the water to cool by itself.Pour ¾ of a cup of vinegar into the plastic bottle. Add half a cup of the pink cabbage water to the vinegar.Note the colour of the liquid in the bottle.Carefully add the baking soda into the bottle. Give it a gentle swirl. DO NOT shake it and DO NOT put a lid on the bottle.Note what happens and specifically any change in color.
Results
There are 2 things that happen: There is a lot of bubbling. The color changes from pink to blue. Conclusion
For an explanation of the bubbling see another one of the chemistry project ideas on this site - the experiment What a gas!
As for the color change, which is what this experiment is actually all about, it all has to do with pH. Vinegar is acidic, which means it has a low pH (below 7, which neutral – or half way). As the experiment takes place, the pH changes, it becomes higher. The color of the water changes as the pH changes. So more acid = pink. Less acidic (or more alkaline) = blue. Hey presto - you have a natural indicator!
More chemistry project ideas.
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