Balancing Chemical Equations (3.1.3) Flashcards
• In balancing a chemical equation, start with the compound with the greatest diversity of atoms, and balance pure elements last; when there is not an obvious
starting point, begin with the first compound.
• In balancing a chemical equation, start with the compound with the greatest diversity of atoms, and balance pure elements last; when there is not an obvious
starting point, begin with the first compound.
• In a balanced chemical equation, all coefficients must be whole numbers and the number of atoms of each type of element must be the same on both sides of the
equation.
• In a balanced chemical equation, all coefficients must be whole numbers and the number of atoms of each type of element must be the same on both sides of the
equation.
Rules to balance a chemical equation:
- Start with the compound with the greatest
diversity of atoms. - Leave pure elements for last.
- If rule 1 does not indicate where to start, begin
with the first compound.
Apply rule 1 and start with the first compound on the
right side, potassium bicarbonate (KHCO3). Place a
“1” before it because there is a single potassium
atom in the first compound on the left and a single
carbon atom in the second compound of the left.
Do not try to balance O2 yet, since it is a pure
element (rule 2). Rule 3 need not be applied here.
Balance the potassium by placing a “1” in front of
the potassium dioxide (KO2). Balance the carbon by
doing the same for carbon dioxide (CO2).
Next, balance the hydrogen atoms by temporarily
putting a “½” in front of the water molecule. Note
that rule 2 is still being followed.
Balance the number of oxygen atoms on both sides.
To do this, set the coefficient of O2 to x and solve for
it algebraically.
The final rules are:
4. All coefficients m
ust be whole numbers, which may require multiplying through by the least common multiple to remove fractions.
5. The number of atoms of each element must be
balanced on both sides.
Following rule 4, multiply the entire equation by the
lowest common multiple, in this case the “4” in the
denominator of the coefficient for O2.
As a final step, verify that the number of atoms of
each element balance (rule 5).
Rules to balance a chemical equation:
- Start with the compound with the greatest
diversity of atoms. - Leave pure elements for last.
- If rule 1 does not indicate where to start, begin
with the first compound.
Apply rule 1 and start with the first compound on the
right side, potassium bicarbonate (KHCO3). Place a
“1” before it because there is a single potassium
atom in the first compound on the left and a single
carbon atom in the second compound of the left.
Do not try to balance O2 yet, since it is a pure
element (rule 2). Rule 3 need not be applied here.
Balance the potassium by placing a “1” in front of
the potassium dioxide (KO2). Balance the carbon by
doing the same for carbon dioxide (CO2).
Next, balance the hydrogen atoms by temporarily
putting a “½” in front of the water molecule. Note
that rule 2 is still being followed.
Balance the number of oxygen atoms on both sides.
To do this, set the coefficient of O2 to x and solve for
it algebraically.
The final rules are:
4. All coefficients m
ust be whole numbers, which may require multiplying through by the least common multiple to remove fractions.
5. The number of atoms of each element must be
balanced on both sides.
Following rule 4, multiply the entire equation by the
lowest common multiple, in this case the “4” in the
denominator of the coefficient for O2.
As a final step, verify that the number of atoms of
each element balance (rule 5).
