Disappearing Gum

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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What you'll need

• Chewing gum - candy coated pieces like gum-balls or Chiclets are best, but any stick or piece of bubblegum will work.
• Chocolate - milk chocolate like Hershey's Kisses or plain Halloween-sized candy bars are best.

experimental procedure

1. Chew the gum in your mouth for a minute or two.
   
2. Take the gum out of your mouth (yes, really) and compare how it looks now compared to  how it looked before you chewed it.
   
3. Put the gum back in your mouth, then also put a piece of chocolate in your mouth and chew them together. 
   
4. After another minute or two take the gum (and any chocolate that may be left) out of your mouth.  What does it look like now?  Is it still sticky?
   
5. Put it back in your mouth and keep chewing.  What happens to the gum?  If you have more chocolate add that to your mouth and continue chewing.  Can you make the gum disappear?
   

what's happening

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?

Coming soon:

make rock candy
float letters off M&M's
pop rocks
dancing raisins
carbonated soft drinks
Lava Lamps
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

Journal of Chemistry Education Classroom Activity #105. A Sticky Situation: Chewing Gum and Solubility 

• https://pubs.acs.org/doi/pdf/10.1021/ed800135j

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Learn more about solubility:

• https://en.wikipedia.org/wiki/Solubility

Coming soon:

Saliva
​Digestion
​Solubility experiments

​Subject Tags
​

• Food Chemistry
• Kitchen Science
  
• Oils
  
• Polymers
• ​Water
  

All Chemistry Subject Tags

All
Acid/Base Chemistry
Bubbles
Crystals
Density
Food Chemistry
Heat/Cold
Kitchen Science
Milk Chemistry
Oils
Phase/State Changes
Polymers
Soap
Water

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