Water is decomposed by electrolysis to form the gaseous products hydrogen, #H_2#, and oxygen, #O_2#. How do you write the balanced equation for this reaction?

1 Answer
Bio
Jan 28, 2016

#2"H"_2"O" -> 2"H"_2 + "O"_2#

Explanation:

One molecule of water #"H"_2"O"# can give 2 Hydrogen and 1 Oxygen atom, which is sufficient to make 1 #"H"_2# molecule and #1/2# of a molecule of #"O"_2#. You can write it as

#"H"_2"O" -> "H"_2 + 1/2"O"_2#

However, there is no such thing as half a molecule. To avoid fractions, multiply everywhere by 2. So it becomes

#2"H"_2"O" -> 2"H"_2 + "O"_2#

This means that you can make 2 molecules of #"H"_2# and 1 molecule of #"O"_2# with 2 molecules of #"H"_2"O"#.

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