Page 56 - BBC Knowledge - October 2017 IN

Science
Experiments

SOFT DRINKS

VS YOUR TEETH
We often hear about the dangers of sugary soft drinks, but this eye-opening experiment
shows you that all acidic drinks can be bad for your pearly whites – even the ones you
thought were healthy…

WHAT’S GOING ON?
Egg shells are made of calcium carbonate – a hard mineral that is
YOU WILL similar to calcium phosphate, the substance our teeth are made
NEED: of. Acids react with calcium carbonate, breaking it apart into
l Eggs calcium (which is carried off in the water) and carbon dioxide
l Selection of soft gas. The more acidic a liquid is, the faster the reaction and
drinks (we used the more the shell will weaken. The bubbles and froth that form
orange juice, on the egg and on the surface of the liquid are carbon dioxide
soda, cola and gas, showing that the mineral is quite literally ‘fizzing’ away in
an energy drink) the tart-tasting liquid.
l Tap water (this The results may shock you: orange juice, which is typically
acts as a control, seen as a ‘healthy’ drink, is naturally high in citric acid and
for comparison) causes more dramatic changes than cola. Fizzy water is also
l Enough glasses acidic because it contains dissolved carbon dioxide, which
or mugs for forms carbonic acid. Commercial soft drinks are remarkably
each drink corrosive because manufacturers add extra acids to give them
l Sticky labels a ‘tang’. But it’s energy drinks that are consistently among the
l A toothbrush worst offenders, typically being as acidic as vinegar.

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2
METHOD:
1. Collect a selection of soft drinks.
2. Place an egg in each glass.
3. Pour enough of each drink into separate
glass to completely cover the egg. Don’t
forget to include one with tap water. 3
4. Label each glass and leave overnight.
Leave for a week to witness even more
dramatic results!
5. Carefully remove each egg to examine
the shell.
6. Rub gently with a toothbrush to simulate
4
the effect of brushing your teeth after
exposure to the acidic drinks (see
main image).
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OCTOBER 2017