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
What does a Foucault pendulum demonstrate?
AnswerEarth's rotation
As Earth turns beneath it, a long free-swinging pendulum's swing direction slowly rotates.
Otto von Guericke's Magdeburg hemispheres, which horses could not pull apart, demonstrated the force of what?
AnswerAir pressure
With the air pumped out, outside air pressure held the two hemispheres together.
On which world did an astronaut drop a hammer and a feather to show they fall at the same rate without air?
AnswerThe Moon
On Apollo 15 in 1971, a hammer and a feather dropped on the airless Moon hit the ground together.
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.
A Van de Graaff generator makes a person's hair stand on end because the hairs do what?
AnswerGain the same charge and repel each other
Each hair picks up the same type of charge, and like charges push away from each other.
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