Download Balancing Chemical Equations

Balancing Chemical Equations
The general format for chemical equations is:




a+ b  c +d
The reactants go on the left side of the equation (___ and ____ in this case).
The + sign means ___________________________.
The  means ____________________.
The products go on the right side of the equation (____ and ______ in this case).
Lets work with the statement:
“Hydrogen gas reacts with oxygen gas to form liquid water”
Word Equation
Skeleton Equation
To balance equations numbers called coefficients are put before the formulas. This changes the number of
molecules.
Notes: You cannot add or change subscripts.
You do not write coefficients of 1 (one).
Balanced Equation
Why Must We Balance Equations?
1) Remember the Law of Conservation of Mass states that the total mass of reactants is always equal to
the total mass of the products.
2) Dalton’s Atomic Theory states that atoms can not be created or destroyed. Compounds are formed
when atoms of different elements combine in fixed proportions.
To go from a skeletal equation to a balanced equation, follow these steps:
1) Balance the equation by adding coefficients
– Pick single elements that appear on each side first to balance
– Remember leave O then H until the end
2) Go back and re-check that all atoms are equal on both sides
– If you have any fraction coefficients clear them by multiplying.
– Also, make sure you have the smallest possible coefficients by reducing the ENTIRE
EQUATION.
Example:
Fe + H2O  H2 + Fe2O3
2Fe + 3H2O  3H2 + Fe2O3
Example 1:
Skeletal Equation:
Skeletal
Reactants
Balanced Equation:
Na + H2O  NaOH + H2
Products
Balanced
Reactants
Products
____ Na + ____ H2O  ____ NaOH + ____ H2
Example 2:
Skeletal Equation:
Skeletal
Reactants
Balanced Equation:
Cu + AgNO3  Cu(NO3)2 + Ag
Products
Balanced
Reactants
Products
____ Cu + ____ AgNO3  ____ Cu(NO3)2 + ____ Ag
Example 3:
Skeletal Equation:
Skeletal
Reactants
Balanced Equation:
Ca(NO3)2 + NaOH  Ca(OH)2 + NaNO3
Products
Balanced
Reactants
Products
____ Ca(NO3)2 + ____ NaOH  ____ Ca(OH)2 + _____ NaNO3