Inspiring Learning Chemistry KS3
BUBBLES
What are bubbles? How do bubbles work? What happens when bubbles meet? What makes a super
bubble?
What are bubbles?
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How do bubbles work?
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What happens when a bubble meets another bubble? How is this different to when a bubble meets your
skin?
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Making bubbles last!
What can you add to normal bubble mixture to make them last longer. You have sugar, lemon juice and
glycerin, which one do you think will make the bubbles last the longest?
Hypothesis
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Inspiring Learning Chemistry KS3
Test
How many seconds does each bubble last for in the different solutions?
Bubble mixture
Sugar
Lemon juice
Glycerine
1
2
3
4
Results
Analysis – What have you found?
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Evaluation – What went well and what limitations did you encounter? Which substance would you
recommend for longer lasting bubbles?
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Inspiring Learning Chemistry KS3
What are bubbles?
Bubbles are just a thin film of soap. Transparent and delicate in nature, a mere touch of the finger is
enough to break them. Most bubbles are filled with air and you can make them using gases like carbon
dioxide. The film that makes bubbles is made of three layers. The first layer is a thin layer of water that is
sandwiched between two layers of soap molecules. Each soap molecule is oriented in such a way that its
polar or hydrophilic head f aces the water. At the same time, its hydrophobic hydrocarbon tail is away
from the water layer. No matter what shape a bubble has initially, it will eventually try to become a sphere.
Know what happens when bubbles meet?
Have you tried creating more than one bubble? Instead of stacking over each other, they merge walls in
order to minimise their surface area. In case the two bubbles are of the same size, their walls that separate
them will be flat. If the bubbles are of different sizes, then the smaller bubble will merge into the larger
bubble to form one single large bubble. When bubbles meet, their walls merge to form the shape of
hexagons.
What is bubble solution made of?
Bubble solutions are made of soap. Soap's main ingredient is detergent and it helps form bubbles when it
comes in contact with water. However, detergent also contains some ions that may prevent the bubbles
from forming. Soaps contain a carboxylate group that reacts with calcium and magnesium ions, while
detergents lack this functional group. This is why glycerine is usually added to the solution because it
extends the life of a bubble by forming weak hydrogen bonds with water and also slows down its
evaporation process.
Why add glycerine?
Glycerine, or C3H5(OH)3, is a natural by-product of the soap-making process. Glycerine is produced as the
saponification of the animal fats used to create soap. In fact, the American Dietetic Association classifies
glycerine as a carbohydrate because of its transformation from animal fats. As a finished product, glycerine
is thick, clear and odourless with a slightly sweet taste. Glycerine’s ability to dissolve in water makes it
particularly useful for making bubbles.
Bubbles burst because the outside layer of water evaporates into the surrounding environment. With no
water to hold the spherical structure together, the bubbles pop. Glycerine works by delaying the
dehydration process. Glycerine has the unique properties of being able to produce weak bonds with
hydrogen. These bonds prevent the water from evaporating as quickly. Glycerine is also hygroscopic. This
means that it has the ability to attract water out of the air, which may also contribute to its abilities to
resist evaporation longer.
Inspiring Learning Chemistry KS3
Bouncing Bubbles
A bouncing bubble is amazing because most people have never seen a bubble bounce much less be the
person who actually does the bouncing! Experience shows that bubbles usually burst when they come in
contact with just about anything. Why? A bubble’s worst enemies are oil, dirt, evaporation, and gravity. A
“super” bubble will bounce off of a surface if the surface is free of oil or dirt particles that would normally
cause a break in the thin soap film of the bubble. The problem with gravity and evaporation is that the
water film gets very thin (down to a millionth of an inch) on the top surface as time passes. It finally gets
too thin to hold onto itself and the wall collapses completely. Similar to the way we perceive the colours in
a rainbow or an oil slick, we see the colours in a bubble through the reflection and the refraction of light
waves off the inner and outer surfaces of the bubble wall. You can't colour a bubble since its wall is only a
few millionths of an inch thick. A bubble reflects colour from its surroundings.
Bubble Tennis
You will need
 bubble mixture and large bowl as above
 2 coat hangers
 tube from a ballpoint pen (without the ink cartridge)
What you do
1. Shape the coat hangers until they are in the shape of a circle (~12cm diameter) with a handle.
2. Dip each hanger in the soap solution and pull them out so that a film of soap fills up the whole circle. These are
your bubble racquets.
3. Hold the pen tube by one end and dip the other into the solution for a few seconds.
4. Pull the tube out and blow into the other end, forming a soap bubble. This is your tennis ball.
5. Now you can practice your serve. This may take a little practice and works better if you are able to add glycerine
to the bubble mixture. Make sure your actions are gentle or the bubble and racquet will burst!