Download The complete reaction can be written

The chemical equation for the reaction of methane and oxygen is not yet
properly written because the atoms of the elements on the product side
do not equal the atoms of each element on the reactant side of the
equation. The law of conservation of mass, which states that matter can
neither be created nor destroyed in an ordinary chemical reaction, must
be upheld when writing a chemical equation. This chemical equation is
unbalanced.
Another example:
NaOH + HCl --> ?
Na is Na+, OH is OH-, so this gave us NaOH. Originally the one
positive canceled the one negative
HCl is H+ + Cl -, this gave us HCl.
Reaction is going to be the Na+ reacting with a negatively charged
ion. This will have to be the chlorine, Cl-, because at the moment
the Na+ is tied to the OH-. So: Na+ + Cl- --> NaCl
The H+ from the HCl will react with a negative (-) ion this will be
the OH- from the NaOH. So: H+ + OH- --> H2O (water).
The complete reaction can be written:
NaOH + HCl --> NaCl + H2O. We have equal amounts of all atoms
each side of the equation, so the equation is balanced.
or
Na+OH- + H+Cl- --> Na+Cl- + H+OH-
Coupled Reaction
Exergonic reactions like
burning of glucose drive the
endergonic reaction of ATP
synthesis. The ATP molecule
can then travel to another
part of the cell where it is
broken down to power
another endergonic
reaction like protein
synthesis.