Title: ‘The science of soap bubbles’
Aim: To study the various aspects of science in making soap bubbles
Target group: Transition Year (max 24 pupils)
Equipment needed:
Per Group (groups of 2 or 3)
String (1 metre)
Per class
String (not plastic coated), small enough
to fit through drinking straws. (12 metres)
Few packets of drinking straws
Wire coat hanger (12)
Glass rod (12)
Large tray (to hold soap sol.) (12)
UV lamp (long wave) (One shared)
Stiff wire e.g. heavy gauge copper wire
(12 metres)
12 Plastic bottles and any other material
being used to make loops.
Wire cutters (4 to be shared)
Hot plate (6 to be shared or 3 double
rings)
Scissors (4 to be shared)
500 ml beaker (12)
Graduated cylinder (12)
Selotape
Several plastic drinking straws
Wire coat hanger (1)
Glass rod (1)
Large tray (1)
UV lamp
Stiff wire e.g. heavy gauge copper wire
(1 metre)
Plastic bottle and any other material
being used to make loops.
Wire cutters
Hot plate
Scissors
500 ml beaker (1)
Graduated cylinder (1)
Selotape
Chemicals:
Per Group (groups of 2 or 3)
Soap flakes e.g. Lux
125 ml washing up liquid
1,740 ml (1.75 L)distilled water
85 ml glycerine
Granulated sugar
Per class
Soap flakes e.g. Lux
1,500 ml (1.5 L) washing up liquid
20,880 ml (21L) distilled water
1020 ml (1.02 L) glycerine
Granulated sugar
NOTE! Soap flakes are no longer available on the market, so for this one would
have to grate a bar of soap
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Safety analysis:
Hazard & Risk
Teacher at risk (T)
Student at risk (S)
Level of Risk
Low Medium
Ingestion of chemicals *
with consequent illness
(T&S)
Chemical splash in
*
eyes, skin or on clothes
(T&S)
Spillage of liquids with *
consequent slipping
(T&S)
Glass breakage with
consequent cut (T&S)
Cut oneself when
using wire cutters or
scissors. (T&S)
How to reduce risk
High
Place warning on chemical containers.
Orally warn the class before
commencement.
Wear all protection available e.g. safety
goggles, lab jacket and disposable
gloves.
Wipe up any spills immediately. Lay
down newspaper before beginning
experiment.
Call teacher if any glassware breaks.
Don’t use cracked or damaged
glassware.
Be very careful when using the wire
cutters and scissors. Always cut away
from your body. Teacher collects wire
cutters and scissors when enough
samples have been cut or have wire and
string cut before class and tape ends of
wire for protection against cuts.
*
*
Additional control measures:
 Ensure that students know how to use all equipment safely before starting.
 Ensure that students are familiar with procedure before starting.
 Keep bubbles away from the face.
 Ensure all bags, coats, books etc. are out of the way before starting.
 Keep all equipment away from the side of the bench.
 If any chemicals are ingested-seek medical help immediately and bring the
chemical information sheet with you for the doctor to see.
 If any chemicals splash into eye-wash out with eye wash if available or else
cold water immediately and seek medical attention and bring the chemical
information sheet with you for the doctor to see.
 Always have a fully equipped 1st aid kit close to hand.
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Procedure:
1) Make one bubble loop from wire coat hanger by bending it into a loop and wrapping
some string around it. Make another loop by threading string through two plastic
straws.
NOTE! If making a large loop with string, do so for students before the class because
it is very time consuming.
2) Make up a bubble solution in a large beaker: 10 % washing up liquid, 85 % distilled
water, 5% glycerine. If making 100 ml solution  10 ml washing up liquid, 85 ml
distilled water, 5 ml glycerine. 500 ml solution  50 ml washing up liquid, 425 ml
distilled water, 25 ml glycerine etc.
3) Stir solution (do NOT shake!) with glass rod.
4) Pour bubble solution into a large tray (big enough for bubble loop)
5) Make bubbles!
6) Repeat using other solutions varying the amount of detergent, glycerine etc. and
making loops out of other materials such as wire etc.
Other possible solutions:
TEACHING TIP! Divide the solutions up among the different groups to save on
chemicals and time.




Soap flakes in water alone. (500 ml water and soap flakes). Could try a dilute and
saturated soap solution.
Soap flakes instead of washing up liquid in solution given in procedure. (Soap
flakes, 425 ml distilled water, 25 ml glycerine).
75 ml of washing up liquid, 35 ml glycerine and 390 ml water (Note! When the
detergent conc. exceeds 12% (by volume) the bubbles do not last as long. The best
conc. of glycerine is one half that of detergent.)
50 ml of washing up liquid, 450 ml of sugar syrup (Note! Can also use sugar in
bubble solution to strengthen bubbles (instead of glycerine) by dissolving equal
volumes of granulated sugar and water and heating until dissolved, forming a
sugar syrup).
TEACHING TIP! When heating the sugar solution, one can use a magnetic stirrer if
available, when using a hotplate. Also, put paper down on the ground when using the
sugar solution because it is very sticky!
7) If time permits, try making different shaped frames out of wire and other materials
e.g. plastic bottles etc. Test them with the soap solution. See if you can make bubbles
that are not round!
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Set-up diagram(s):
Sample results/observations:
The bubbles are always round, no matter what shaped frame is used. The sugar
solution was stronger than the glycerine solution.
Conclusions:
Bubbles are round as a result of the surface tension caused by the soap layer on the
surface of the water. In nature, the volume with the smallest surface area is a sphere.
Possible questions to ask:
Can you catch a bubble in your hand? Try wetting your hand?
Does the bubble bounce off your shirt? Why? What about the desk?
Can you explain why all bubbles are round?
Links to Irish curriculum:
Polar/non-polar
Hydrophilic and hydrophobic
Surface tension of water and surface area
Possibly hard and soft water-metal ions etc.
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