The
Witch's Brew
(an effervescence science demonstration)
Equipment:
" a tall thin drinking glass
" 1 flat baking tray
" 2 tablespoons of bicarbonate of soda
" 2 tablespoons of dish washing liquid
" food colouring of your choice
" ½ of a cup of vinegar
Instructions:
1. Place the drinking cup on the tray.
2. Put the bicarbonate of soda and dish washing liquid
into the glass.
3. Add about 6 drops of food colouring & mix into
a paste.
4. Quickly pour the vinegar into the glass.
5. Think, Pair, Share with a partner. - What just happened
and why do you think it happened?
Brief
Explanation:
In
this experiment the fizz is a chemical reaction between
the baking soda and the vinegar. When the 2 chemicals
mix carbon dioxide is produced. The gas then makes bubbles
with the liquid. The dish washing liquid makes the bubbles
last longer and makes foam. Too much gas is produced for
the small glass and as a result spills over the top of
the glass.
Extension:
I believe that you could make this demonstration even
more impressive. Try manipulating the variables (change
stuff) - amounts of chemicals, different detergents, different
container, more / less / different coloured food colouring,
don't mix to paste, add detergent first & put bi-carb
on top. Get experimenting!
Science
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