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Introduction
Atoms are not created or destroyed during a chemical reaction. Scientists know that there must be
the same number of atoms on each side of the equation. To balance the chemical equation, you
must add coefficients in front of the chemical formulas in the equation. You cannot add or change
subscripts!!
Procedures
1. Determine the number of atoms for each element.
2. Pick an element that is not equal on both sides of the equation.
3. Add a coefficient (the large number to the left of the formula) in front of the formula with that
4. Continue adding coefficients until you get the same number of atoms of each element on each
side.
5. If you do not need to add a coefficient, place a “1” in the box.
Ca + O → CaO
N
2
Cu O + C →Cu + CO
2
H
2
+
O
2
→
H O
2
2
2
+
H → NH
2
3
Na + MgF →NaF +Mg
2
Mg + O → MgO
2
Na
+
Al2O3
P4
C
+
+
O2 →
→
Al
Na2O
+
O2
O2 →
P4O10
H2 →
C2H4
Bonus:
C3H5(NO3)3
→ CO2 + N2 + H2O + O2
Balancing Chemical Equations
Name:_________________________________Date__________Period________
The law of conservation of mass states the in a chemical reaction mass cannot be created or destroyed, it can be
rearranged or turned into energy. The following chemical reactions are not balanced. Study the examples below
and then balance the rest of the equations to show that mass was conserved.
Ex—HgO → Hg + O2 balanced it is:
Ex – Mg + HCl →
2HgO→ 2Hg + O2
MgCl + H2 balanced is: 2Mg + 2HCl → 2MgCl + H2
Now balance these equations:
1.
NaCl + AgNO3 → NaNO3 + AgCl
2.
Zn + H2SO4 → ZnSO4 + H2
3.
NaOH + HCl → NaCl + H2O
4.
Al2(SO4)3 + Ca(OH)2 →
5.
H2O2 →
H2 + O2
6.
Cl2 + NaBr
→
7.
Zn + CuSO4 →
8.
KClO3 → KCl + O2
9.
H2O + Fe →
10.
Ca(OH)2 + HNO3 →
11.
Na2O + CO2 →
12.
H2 + N2 → NH3
13.
HgO + Cl2
Al(OH)3 + CaSO4
NaCl + Br2
ZnSO4 + Cu
Fe2O3 + H2
→
Ca(NO3)2 + H2O
Na2CO3
HgCl + O2
14.
Na + Br2 →
15.
Ca(OH)2 + HNO3 →
NaBr
Ca(NO3)2 + H2O
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