What happens if you chew gum and chocolate at the same time? You'll find out in this sweet candy science experiment while learning an important concept in chemistry: solubility.
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This is a chemistry experiment, even though you are doing it in your mouth! It illustrates a very important concept in chemistry called solubility, which is the ability of one substance to dissolve another substance. Chemists say that “like dissolves like” and this is an example of that. If your gum was candy coated, like a Chiclet or gum-ball, you should have noticed that the candy coating dissolved or disappeared as soon as you began chewing. This is because the candy coating was made of sugar, which easily dissolves in water (try adding a spoon full of table sugar to a glass of water and watch what happens), and the saliva in your mouth is mostly water. Chemists would say that sugar is soluble in water. Saliva and chewing are the first steps in digesting or breaking down your food into simpler components that your body can use for energy.
Your saliva does not dissolve the gum, however, because most modern chewing gums are made of a synthetic rubber (i.e. man-made, not natural), which is a type of oil-based polymer, such as butadiene-styrene, vinyl acetate, or polyethylene (the same material in plastic grocery bags). You may have already learned that oil (as well as oil-based substances) and water don't mix- they are not alike. But chocolate does contain oil-based fatty substances, so the chocolate dissolves the gum. Like dissolves like. After adding the first piece of chocolate and chewing you should have noticed that the gum was much softer and stickier, and maybe much smaller than it was after you first chewed the gum alone. If you add enough chocolate to the gum in your mouth (you may need 3 or 4 pieces) and continue chewing you should be able to make the gum disappear completely!
variations and related activities
If you're not allergic to peanuts, try chewing a spoon full of peanut butter with your gum instead of chocolate. Does the peanut butter also make the gum disappear? Why do you think that is?
Instead of doing the entire experiment in your mouth, just chew the gum for a minute or two in your mouth, then put it in a cup or small bowl instead. Add a couple spoonfuls of vegetable oil to the cup and use a spoon to stir and grind the gum. Does it dissolve? If not, add a little more vegetable oil. Try repeating ths experiment with some other liquids. Is gum more or less soluble in other liquids?
Solubility has it's limits, however, and you can easily test this. Add one or two spoonfuls of sugar to a glass of water and observe what happens. Does all of the sugar dissolve immediately? Observe for a minute or two, has more dissolved? Use a spoon tp stir the water and sugar. Does it dissolve more easily? Try adding more spoonfuls of sugar and stirring. Does the sugar continue to dissolve? Keep adding sugar until it will no longer dissolve in the water. Now you have reached the solubility limit- the water simply can't hold any more sugar and we say it is saturated. What would happen if you added more water to the glass? Solubility also depends temperature. With the help of an adult try repeating this experiment with warm or hot water. Is sugar more soluble in hot water, i.e. can you make more spoonfuls of sugar dissolve?
make rock candy
float letters off M&M's
carbonated soft drinks
Dissolve egg shell in vinegar
Underwater fireworks (food coloring dissolves in water but not oil)
Oil-based and water-based paints
references and links to more information
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