Balancing Chemical Equations

1. The same number of atoms of each element appearing in reactants must appear in the products.

2. The subscripts of a formula cannot be changed to balance the equation.

3. Choose compound with greatest number of atoms first.

4. Balance by placing necessary coefficients in front of entire molecules. NO SUBSCRIPT CHANGES!

5. Be certain each side of equation has same number of atoms of each type.

6. Make sure coefficients are in lowest whole number ratios.

7. Polyatomic ions usually stay intact, but multiple polyatomic ions may be separated.

8. (aq.) stands for aqueous which is Latin for water solution:

(g) gas (l) liquid (s) solid (c) crystalline solid

means “yields” and shows direction of action

∆ above arrow shows heat has been added

shows reaction is reversible

MINHO: try Metals first, then Ions, then Nonmetals, and Hydrogen, then Oxygen last

C8H18 + O2 CO2 + H2O C8H18 + O2 __ CO2 + __ H2O

C8H18 + __ O2 __ CO2 + __ H2O

__ C8H18 + __ O2 __ CO2 + __ H2O

H2CrO4 + AgNO3 Ag2CrO4 + HNO3 (aq) (aq) (s)

(aq)

Chromic + Silver Silver + NitricAcid Nitrate Chromate Acid

1, 2, 1, 2 Double displacement

Cu(NO3)2 CuO + NO2 + O2 (aq) (s) (g)

(g)

Copper (II) Copper (II) + Nitrogen + Oxygen

Nitrate Oxide Dioxide Gas

2, 2, 4, 1 Decomposition

AlBr3 + Cl2 AlCl3 + Br2 (aq) (g) (aq) (g)

Aluminum + Chlorine Aluminum + Bromine

Bromide Gas Chloride Gas

2, 3, 2, 3 Single Displacement

P4 + O2 + H2O H3PO4 (s) (g) (aq) (aq)

Phosphorus + Oxygen + Water Phosphoric

(free) gas acid

1, 5, 6, 4 Synthesis

sodium permanganate + sulfuric acid sodium sulfate + manganese (VII) oxide + water

NaMnO4 + H2SO4 Na2SO4 + Mn2O7 + H2O

(aq) (aq) (aq) (s) (l)

2, 1, 1, 1, 1 Double Displacement

Th(NO3)4 + K3PO4 Th3(PO4)4 + KNO3 (aq) (aq) (s)

(aq)

Thorium + Potassium Thorium + Potassium

Nitrate Phosphate Phosphate Nitrate

3, 4, 1, 12 Double Displacement

sulfur trioxide + nitric acid sulfuric acid + nitrogen (V) oxide

SO3 + HNO3 H2SO4 + N2O5 (g) (aq) (aq) (g)

1, 2, 1, 1 Double Displacement

NH4NO3 + Ca(OH)2 Ca(NO3)2 + NH3 + H2O

(aq) (aq) (aq) (g) (l)

Ammonium + Calcium Calcium + Ammonia + water

Nitrate Hydroxide Nitrate

2, 1, 1, 2, 2 Double Displacement

sodium chloride + potassium iodide

NaCl + KI ________ + _________ (aq) (aq) (?)

(?)

Does a reaction take place?

CuSO4 + H3PO4 _____ + ______ (aq) (aq)

A)3, 1, 2, 1B)3, 1, 1, 3C)2, 3, 3, 2D)3, 2, 1, 3E)2, 3, 3, 1

((D))Copper (II) + Phosphoric Copper (II) +

SulfuricSulfate Acid Phosphate

Acid

Mg(OH)2 + H3PO4 _____ + ______ (aq) (aq)A.1, 1, 1, 1B.3, 2, 1, 3C.2, 3, 1, 6D.2, 3, 1, 1E.3, 2, 1, 6

((E.))Magnesium + Phosphoric Magnesium +

WaterHydroxide Acid Phosphate

CuCl2 + Na3PO4 _____ + ______ (aq) (aq)A.1, 2, 1, 2B.2, 3, 1, 6C.2, 3, 1, 1D.3, 2, 1, 6E.1, 1, 1, 1

((D))Copper (II) + Sodium Copper (II) + SodiumChloride Phosphate Phosphate Chloride

Potassium + Nickel (II) _____ + ______

Permanganate NitrateA.2, 1, 2, 1B.2, 1, 3, 1C.1, 2, 1, 2D.1, 2, 1, 3E. 1, 1, 1, 1

((A))KMnO4 + Ni(NO3)2 KNO3 + Ni(MnO4)2

KMnO4 + Na2C2O4 + H2SO4

K2SO4 + Na2SO4 + MnSO4 + CO2 + H2O