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2+
and other gases. Here’s the Fe + S Fe S 2+
reaction for the burning of
Note that oxygen is not involved to
methane (CH 4) which gives carbon
create iron sulfide. (This
dioxide (CO 2) and water (H 2O):
experiment can even be done in a
CH 4 + 2 O 2 CO 2 + 2 H 2O container without oxygen.)
Synthesis: This reaction happens The chemical reaction inside
when simple compounds come electrochemical cells is also a redox
together to form a more reaction. Batteries (also known as
complicated compound (A + B galvanic or voltaic cells) use a
AB). The iron (Fe) in a nail spontaneous chemical reaction
combines with oxygen (O 2) to form inside to create energy. The acid
rust, also called iron oxide (Fe 2O 3). inside the battery reacts with the
metal electrodes (the plus and
2Fe + O 2 Fe 2O 3
minus ends of the battery) to
Oxidation-Reduction (Redox
provide electricity (energy).
Reaction): Redox reactions
Non-spontaneous cells require an
involve electrons zipping around
energy source (like a battery) in
between compounds. Anytime you
order for the chemical reaction to
have an oxidation, you also have a
occur. When you break apart the
reduction process, hence the term
water molecule into hydrogen and
redox.
oxygen (electrolysis), it requires
Oxidation happens when a energy.
compound loses electrons
Back in 1800,
(increases oxidation state) and
William
reduction occurs when a compound
Nicholson and
gains electrons (decrease in
Johann Ritter
oxidation state). In this reaction,
were the first
the magnesium is oxidized and the
ones to split
carbon dioxide is reduced:
water into
2Mg + CO 2 2 MgO + C
hydrogen and oxygen using
You do not need oxygen to have a electrolysis. (Soon afterwards,
redox reaction. In fact, you can Ritter went on to figure out
have combustion without oxygen electroplating.) They added energy
when you combine iron (Fe) and in the form of an electric current
sulfur (S) to get iron sulfide into a cup of water and captured
2+
2+
(Fe S ): the bubbles forming into two
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