Balancing Chemical Equations

Little number after an element in a chemical equation (e.g., H₂)

• Coefficient

• Subscript

• Superscript

• Element Number

Total atoms in 5Na₃PO₄

• 30

• 35

• 40

• 45

Right part of a chemical equation: 2H₂ + O₂ → 2H₂O

• Reactants

• Products

• Catalysts

• Inhibitors

Law of Conservation of Mass:

• Matter can be created in a chemical reaction.

• Matter can be lost in a chemical reaction.

• Matter cannot be gained or lost in a chemical reaction.

• Matter can change forms but is not conserved.

Atoms in serotonin (C10H12N2O)

• 20

• 22

• 25

• 30

Mn atoms in 3Cr(MnO₄)₆

• 12

• 15

• 18

• 21

Compounds with 2x O than H: H₃PO₄, H₂SO₄, HClO₃, H₂O

• H₃PO₄

• H₂SO₄

• HClO₃

• H₂O

Balanced reaction?

NaHCO₃ → Na₂CO₃ + H₂O + CO₂

• yes

• no

• partially

• depends on conditions

Left part of a chemical equation: 2H₂ + O₂ → 2H₂O

• Products

• Reactants

• Catalysts

• Solvents

Is the equation balanced?

Equation: Al + O₂ → 2Al₂O₃

• Yes, it is balanced.

• No!

• It is partially balanced.

• It cannot be determined.