Download Balancing Equations

Balancing
Equations
The Law of Conservation of
Mass (or Matter)
In a chemical reaction,
matter is neither
created nor destroyed.
Therefore…
• What begins in a chemical
reaction can be found in the
end of a chemical reaction.
• What goes in, must come
out.
The Meaning of a Chemical
Equation
• They tell us…
• What substances are reacting
• What substances are
produced
• The ratios of substances
reacting to those being
produced
Reactants
The reactants are on the left
side of a chemical equation
2H2 + O2
2H2O
Reactants
Products
The products are on the right
side
2H2 + O2
Product
2H2O
Question?
However, you might ask, "On
the left and right side of what?"
Answer - the arrow
2H2 + O2
2H2O
• On the left side are the
reactants - hydrogen and
oxygen
• On the right side is the
product - water
Ca(H2PO4)2 + CaSO4 + HF
Ca10F2(PO4)6 + H2SO4
There can be one, two, three, or
more substances on either
side of the arrow as in the
above example.
Coefficients
Coefficients are the numbers in
front of the formulas.
2 H2 + O 2
2 H2O
COEFFICIENTS
• The coefficients give the number
of molecules (or atoms) involved
in the reaction. In the example
reaction, two molecules of
hydrogen react with one molecule
of oxygen and produce two
molecules of water.
3 Important Things
• One: Reactants are on the left and
products are on the right. Of what? The
arrow
• Two: Coefficients are the numbers in front
of each formula. If no number is shown, a
one is understood.
• Three: The coefficients tell us how many
molecules of each reactant used and how
many molecules of each product made.
Identify the reactants, the products and
the coefficients of these
equations:
1) Zn + 2 HCl ---> ZnCl2 + H2
2) 2 KClO3 ---> 2 KCl + 3 O2
3) S8 + 24 F2 ---> 8 SF6
4) 4 Fe + 3 O2 ---> 2 Fe2O3
5) 2 C2H6 + 7 O2 ---> 4 CO2 + 6 H2O