Joseph Priestley invented the
carbonation process in 1767. And couple years later, a Swiss scientist - Jacob
Schweppe created the world’s first soft drink: Schweppe’s Tonic Water!
Opening a can of Coca-Cola,
what’s you see first? The fizzing sound or the sight of bubbles rising. Well, that
fizz is a chemical process and in fact, this is pretty cool chemistry going on
right inside each tiny can of frizzy drink.
WHY IS IT FIZZY?
Do you enjoy the feeling of
bubbles bursting in your mouths while drinking coke?
These bubbles happen because of
carbonation which occurs when carbon dioxide (CO2) dissolves in water (H2O). CO2
needs a special condition to be easily dissolved, therefore, manufacturers need
to increase the pressure in the can/bottle and keep it at a low temperature. Then,
the can is then sealed so that it is airtight so the CO2 molecules will not
escape. Inside the can, some CO2 dissolves in water, some others sit in gas
form between the top of the bottle or can and the liquid.
WHAT CHEMICAL REACTIONS ARE GOING ON?
When CO2 dissolves in H2O, they
react to form a dilute solution of carbonic acid (H2CO3).H2O + CO2 ⇋ H2CO3
The symbol ⇋ in the chemical equation shows
that the reaction is reversible. That means the carbonic acid can be converted
back to water and carbon dioxide. When a can of pop is sealed, high pressure
inside the can forces the carbonic acid to stay still.
But when you open that can, the
pressure is released. Backward reaction of carbonic acid to form water and
carbon dioxide will happen.
The gaseous CO2 at the top of the
can will now escape. And since the can is no longer under pressure, the
dissolved CO2 starts coming out of the solution. This forms bubbles, which
release the CO2 into the air.
WHY DOES FIZZ TASTE SO GOOD?
The dilute carbonic acid creates
a slight burning sensation on your tongue.
As CO2 bubbles away from the
liquid, the reactants and products move again towards equilibrium. This causes
the backward reaction to take over. As that happens, the concentration of
carbonic acid in the drink gets lower and lower. As the amount of H2CO3 in the
beverage goes down, so does the soda’s ability to bring about that tingling
sensation on your tongue.
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