YEARS K–6 IDEAS FOR THE CLASSROOM
Just Because it Looks like Water, Doesn’t Mean it Is!
By Mary-Anne Kefaloukos
With older students, you can introduce Litmus paper or Universal
Indicator paper or liquid. Observe how the unknown chemicals
change colour (or the indicator paper changes colour) as they tell
us the pH of the chemicals in each of the glasses, then compare
to the known chemicals.
A collection of chemistry demonstrations to teach your Kindergarten
to Year 6 students to be wary of chemicals just lying around.
“Willy was a little boy, but now he is no more, for what he
thought was H 2 0, was H 2 SO 4 ”
This clever and slightly macabre rhyme has been stuck with
me since High School. I can’t take a chemistry class without
reminding my students of it. It led me to develop the following
lesson based on classic chemistry experiments to teach my
students that safety must come first and then curiosity can follow.
You can use the following fun chemistry demonstrations to teach
your students that not everything is water, even if it appears,
smells or behaves like water. These experiments are so exciting
for students to watch, and if you demonstrate them in order, they
build up suspense as well as helping the students make more
informed predictions of the results.
1) Observations and pH tests of water, vinegar
and hydrogen peroxide 3%
Water, hydrogen peroxide 3% and white vinegar
Pour each of the chemicals into identical glass or clear plastic
cups and place them side by side. Ask your students to observe
any differences in the way the chemicals look or behave when
agitated with a spoon. Pose the scenario to the class that you
found these cups sitting on your kitchen table after working hard
in the garden, and ask them if you should take your chances
and have a drink of one. Then talk about how you can test the
chemicals to find out what they are. Consider having three known
chemicals that are labelled next to the ones that are not. By
testing comparatively with known samples, you can determine
the identity of the unknown chemical samples.
2) Vinegar and Bicarbonate of Soda
Experiment
In this experiment, water is being compared with vinegar.
Materials and Method: 2 teaspoons of bicarbonate of soda, 50–
100mL white vinegar, small pop-top bottle
1. Place the bicarbonate of soda into the bottle.
2. Pour in the vinegar and observe the chemical reaction. The
chemical reaction should produce rising bubbling that pours
out of the pop-top bottle.
Start with using sight as your first observation. Ask the students
if they can see any similarities or differences in colour. You
can also shake or agitate the chemical to have a look at how it
behaves (is it thick like honey? will this observation help us tell
the chemicals apart?). You can demonstrate how to smell the
chemicals properly by waving your hand over the cup to move
the smell into your nose, but I don’t recommend giving this task
to your students to do themselves. Discuss with the class if these
simple observations are enough for us to feel confident to pick
one to drink if we found it on a table.
3. Repeat the experiment but this time with water. Ask the
students to observe the differences in reactions that occur.
How to take this experiment up a notch:
When mixing vinegar and bicarbonate of soda, place a balloon
over the pop-top lid and observe how the carbon dioxide released
form the chemical reaction fills up the balloon.
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SCIENCE EDUCATIONAL NEWS VOL 67 NO 1