Balancing Chemical Equations

Overview

• Focus on how to balance chemical equations.
• Start with combustion reactions as examples.

Combustion Reaction: Propane (C3H8)

1. Chemical Formula: C3H8 + O2 → CO2 + H2O
2. Balancing Steps:
   • Balance Carbon (C): 3 C on the left → 3 CO2 on the right.
   • Balance Hydrogen (H): 8 H on the left → 4 H2O on the right (8 divided by 2).
   • Balance Oxygen (O): 10 O total on the right (6 from 3 CO2 + 4 from 4 H2O) → 5 O2 on the left.
3. Final Balanced Equation:
   • C3H8 + 5 O2 → 3 CO2 + 4 H2O

Second Example: Butane (C4H10)

1. Chemical Formula: C4H10 + O2 → CO2 + H2O
2. Balancing Steps:
   • Balance Carbon (C): 4 C on the left → 4 CO2 on the right.
   • Balance Hydrogen (H): 10 H on the left → 5 H2O on the right.
   • Balance Oxygen (O): 13 O total on the right → 13/2 O2 on the left.
   • Convert to Whole Numbers: Multiply the entire equation by 2.
3. Final Balanced Equation:
   • 2 C4H10 + 13 O2 → 8 CO2 + 10 H2O

Example: Aluminum + Hydrochloric Acid

1. Chemical Formula: Al + HCl → AlCl3 + H2
2. Balancing Steps:
   • Balance Chlorine (Cl): 3 Cl on the right → 6 HCl on the left.
   • Balance Hydrogen (H): 6 H on the left → 3 H2 on the right.
   • Balance Aluminum (Al): 2 Al on the right → 2 Al on the left.
3. Final Balanced Equation:
   • 2 Al + 6 HCl → 2 AlCl3 + 3 H2

Example: Gallium + Copper Bromide

1. Chemical Formula: Ga + CuBr → GaBr3 + Cu
2. Balancing Steps:
   • Balance Bromine (Br): 2 Br on the left → 3 CuBr on the left.
   • Use LCM: Get 6 Br on both sides.
   • Balance Copper (Cu): 3 Cu on the left → 3 Cu on the right.
   • Balance Gallium (Ga): 2 Ga on the left.
3. Final Balanced Equation:
   • 2 Ga + 3 CuBr → 2 GaBr3 + 3 Cu

Example: Iodine and Fluorine

1. Chemical Formula: I2 + F2 → IF7
2. Balancing Steps:
   • Use LCM for Fluorine: 14 total on both sides.
3. Final Balanced Equation:
   • 2 I2 + 7 F2 → 14 IF7

Example: Sulfur Dioxide + Oxygen

1. Chemical Formula: SO2 + O2 → SO3
2. Balancing Steps:
   • Balance Oxygen: 4 O on the left → 2 SO3 on the right.
   • Convert to Whole Numbers: Multiply by 2.
3. Final Balanced Equation:
   • 2 SO2 + 1 O2 → 2 SO3

Example: Sodium and Sulfur

1. Chemical Formula: Na + S8 → Na2S
2. Balancing Steps:
   • Balance Sulfur: 8 on left → 8 on right.
   • Balance Sodium: 16 on the right → 16 on the left.
3. Final Balanced Equation:
   • 16 Na + S8 → 8 Na2S

Double Replacement Reaction: Sodium Phosphate + Magnesium Chloride

1. Chemical Formula: Na3PO4 + MgCl2 → NaCl + Mg3(PO4)2
2. Balancing Steps:
   • Balance Phosphate (PO4): 2 on the right → 2 on the left.
   • Balance Sodium (Na): 6 on both sides.
   • Balance Magnesium (Mg): 3 on both sides.
3. Final Balanced Equation:
   • 3 Na3PO4 + 2 MgCl2 → 6 NaCl + 1 Mg3(PO4)2

Example: Potassium Sulfate + Aluminum Chloride

1. Chemical Formula: K2SO4 + AlCl3 → KCl + Al2(SO4)3
2. Balancing Steps:
   • Balance Sulfate (SO4): 3 on the right → 3 on the left.
   • Balance Aluminum (Al): 2 on both sides.
   • Balance Chlorine (Cl): 6 on both sides.
3. Final Balanced Equation:
   • 3 K2SO4 + 2 AlCl3 → 6 KCl + 1 Al2(SO4)3

Final Example: Ammonia + Oxygen

1. Chemical Formula: NH3 + O2 → NO + H2O
2. Balancing Steps:
   • Balance Hydrogen: 6 on both sides.
   • Balance Nitrogen: 2 on both sides.
   • Balance Oxygen: 10 on both sides (5 O2).
3. Final Balanced Equation:
   • 4 NH3 + 5 O2 → 4 NO + 6 H2O

Summary

• Balancing chemical equations requires ensuring equal numbers of each type of atom on both sides.
• Different strategies may be used depending on the equation type and the number of atoms involved.