Mixing baking soda and vinegar produces bubbles of which gas?
AnswerCarbon dioxide
The acid in vinegar reacts with sodium bicarbonate to release carbon dioxide gas.
Science · Facts & stats
Demo facts & stats
7 fact-checked facts about science demonstrations, each with the reason behind it. 5 more are in today's round and join this page after it closes.
The basics
A lemon with a copper coin and a zinc nail stuck into it can produce what?
AnswerA small electric voltage
The two different metals and the acidic juice act as a simple battery that creates a small voltage.
Going deeper
The swinging balls of a Newton's cradle are a classic demonstration of the conservation of which quantity?
AnswerMomentum
When one ball strikes the row, momentum passes through and one ball swings out the other side.
What does a Foucault pendulum demonstrate?
AnswerEarth's rotation
As Earth turns beneath it, a long free-swinging pendulum's swing direction slowly rotates.
The 'elephant toothpaste' foam demo works by rapidly breaking down which chemical?
AnswerHydrogen peroxide
A catalyst quickly splits hydrogen peroxide into water and oxygen, which gets trapped in soapy foam.
Expert level
In the classic 'egg into a bottle' demo, what actually pushes the egg into the bottle?
AnswerOutside air pressure, after the air inside cools
Heated air inside the bottle cools and its pressure drops, so higher outside air pressure pushes the egg in.
In a flame test demo, compounds containing sodium turn a flame which color?
AnswerYellow-orange
Sodium atoms emit strong yellow-orange light when heated; copper gives green and potassium lilac.
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