What is oxidation?
In simple terms, oxidation is a loss of electrons in an element or a compound in contact with the oxygen in the air. Some elements, such as Sodium, Magnesium and Iron lose electrons more easily than the others - we say they are easily oxidized. On the other hand, there are elements that hold their electrons more tightly, like Nitrogen and Chlorine - they are hard to oxidize.
What are the antioxidants?
Antioxidants are the molecules that prevent oxidation in other molecules. Why is that important? Life on Earth requires oxygen for its survival. However, oxidation in our body can lead to the production of the free radicals which may damage our cells.
Antioxidants are slowing down that process of oxidation - in theory, they could slow down aging process and prevent development of certain diseases. Best known antioxidants in the human body are vitamins C and E.
Science behind apple oxidation experiment
Why is apple quickly turning brown when peeled off or sliced? When the inner part of the apple is exposed to an air, process of oxidation occurs. That’s because an oxygen-reactive enzyme is found under the surface (skin) layer.
Citric acid from the lemon serves as an antioxidant in our experiment. All acids slow down the process of oxidation because of their low pH. Oxygen will first react with an acid and only when all acid has been depleted will it react with the apple enzymes. Then we will see an apple turning brown.
Materials needed for apple oxidation experiment:
- Apple
- Lemon
- Cup
- Brush
- Knife
Instructions for apple oxidation eksperiment:
For a step by step instruction on how to do this experiment, watch the video at the beginning of an article.
- Take a half of the lemon and squeeze it into a cup
- Cut an apple in half, so you have 2 halves
- Take a brush, dip it into the lemon juice and spread it over the one half of an apple
- Leave it like that for a few hours. Check it out every hour, you should notice first differences after an hour.
- Check the state of your apple halves after 1, 2 and 3 hours and talk with your child about observed effects.
What will you learn and develop by doing apple oxidation experiment:
- Formulating hypothesis, planning scientific experiment and observing results
- Logical thinking
- Chemical processes, oxidation, antioxidants
If you enjoyed this experiment and would like to do more experiments with simple ingredients, check out How to make sugar crystals, How to make plastic from milk and vinegar and How to make homemade playdough. Enjoy learning science!
