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Unit 12: Alternative Energy Page 21 of 31
Back to splitting the water If we have a glass of water and
molecule – as the electricity zips dump in a handful of salt, the NaCl
+
through your wires, the water (salt) molecule splits into Na and
-
molecule breaks apart into smaller Cl .
pieces: hydrogen ions (positively When we plunk in one positive
charged hydrogen) and oxygen electrode and one negative
ions (negatively charged oxygen). electrode and crank up the power,
Remember that a battery has a we find that opposites attract: Na
+
plus and a minus charge to it, and zooms over to the negative
that positive and negative attract electrode and Cl zips over to the
-
each other. positive. The ions (charged atoms
Na (sodium) and Cl (chlorine) in
So, the positive hydrogen ions zip
over to the negative terminal and this case) are attracted to the
form tiny bubbles right on the wire. opposite electrode and there is
Same thing happens on the current in the solution.
positive battery wire. After a bit of Electrochemistry studies chemical
time, the ions form a larger gas reactions that generate a voltage
bubble. and vice versa (when a voltage
drives a chemical reaction), called
If you stick a cup over each wire, oxidation and reduction (redox)
you can capture the bubbles and reactions. When electrons are
when you’re ready, ignite each to transferred between molecules, it’s
verify which is which. We covered a redox process.
the basics of electrolysis in Unit 8, Fruit batteries use electrolytes
and now we’re going to show you (solution containing free ions, like
how to store the energy and use it salt water or lemon juice) to
power a small car in our generate a voltage. Think of
experiments together.
electrolytes as a material that
dissolves in water to make a
Energy from Food
solution that conducts electricity.
The basic idea of Fruit batteries also need electrodes
electrochemistry is made of conductive material, like
that charged metal. Metals are conductors not
atoms (ions) can because electricity passes through
be electrically them, but because they contain
directed from one electrons that can move (covered
place to the other.
in Unit 10). Think of the metal wire
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