1. Balancing, Writing, and Naming Equations
Balancing Equations
Balancing, Writing, and Naming Equations

2. Balancing Equations

3. Balancing Equations Law of Conservation of Matter:
In a chemical reaction, matter can be neither created nor destroyed.
In a chemical reaction, the amount of reactants equal the amount of products.

4. Balancing Equations Paraphrase: Law of Conservation of Atoms:
The number of atoms of each type of element must be the same on each side of the equation.

5. Hydrogen + oxygen water
Balancing Equations
Hydrogen + oxygen water
H2 + O H2O
Hydrogen and oxygen are diatomic elements.
Their subscripts cannot be changed.
The subscripts on water cannot be changed.

6. Balancing Equation H2 + O2 H2O Count the atoms on each side.
Reactant side: 2 atoms H and 2 atoms O
Product side: 2 atoms H and 1 atom O

7. Balancing Equations H2 + O2 H2O
If the subscripts cannot be altered, how can the atoms be made equal?
Adjust the number of molecules by changing the coefficients.

8. Balancing Equations H2 + O2 2H2O
Reactants: 2 atoms of H and 2 atoms of O
Products: 4 atoms of H and 2 atoms of O
H is no longer balanced!

9. Balancing Equations 2H2 + O2 2H2O
Reactant side: 4 atoms of H and 2 atoms of O
Product side: 4 atoms of H and 2 atoms of O
It’s Balanced!

10. Nitrogen + hydrogen ammonia
Balancing Equations
N2 + H NH3
Nitrogen + hydrogen ammonia
Count atoms.
Reactants: 2 atoms N and 2 atoms H
Products: 1 atom N and 3 atoms of NH3

11. Balancing Equations N2 + H2 2NH3 Nothing is balanced.
Balance the nitrogen first by placing a coefficient of 2 in front of the NH3.
N2 + H NH3

12. Balancing Equations N2 + 3H2 2NH3 Hydrogen is not balanced.
Place a 3 in front of H2.
Reactant side: 2 atoms N, 6 atoms H
Product side: 2 atoms N, 6 atoms H
N H NH3

13. Balancing Equations Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4 Count atoms.
Reactants: Ca – 3 atoms, P – 2 atoms, O – 8 atoms; H – atoms, S – 1 atom, O – 4 atoms

14. Balancing Equations Side note on Ca3(PO4)2
The subscript after the phosphate indicates two phosphate groups.
This means two PO43- groups with two P and eight O atoms.

15. Balancing Equations Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4
Count atoms in the product.
Ca atoms – 1, S atom – 1, O atoms – 4; H atoms – 3, P atom – 1, O atoms - 4

16. Balancing Equations Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4
In this equation, the ion groups do not break up.
Instead of counting individual atoms, ion groups may be counted.
Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4

17. Balancing Equations Ca3(PO4)2 + H2SO4 CaSO4 + H3PO4
Reactants: Ca2+ – 3, PO , H+ – 2, SO
Products: Ca2+ - 1, SO , H+ - 3, PO

18. Balancing Equations Ca3(PO4)2 + H2SO4 3CaSO4 + H3PO4
Balance the metal first by placing a coefficient of 3 in front of CaSO4.
Products: Ca – 3 atoms, SO groups
Ca3(PO4)2 + H2SO CaSO4 + H3PO4

19. Balancing Equations Ca3(PO4)2 + 3H2SO4 3CaSO4 + H3PO4
Three sulfate groups are needed on the reactant side so place a coefficient of 3 in front of H2SO4.
3H2SO4 gives 6 H+ and 3 SO42-.
Neither phosphate nor calcium is balanced.
Ca3(PO4) H2SO CaSO4 + H3PO4

20. Balancing Equations Ca3(PO4)2 + 3H2SO4 3CaSO4 + 2H3PO4
A coefficient of 2 placed in front of H3PO4 which balances both hydrogen and phosphate.
Ca3(PO4) H2SO CaSO H3PO4

21. Balancing Equations Cu + H2SO4 CuSO4 + H2O + SO2
The sulfate group breaks up. Each atom must be counted individually. Ugh!
Reactants: Cu – 1, H – 2, S – 1, O – 4
Products: Cu – 1, S – 1, O - 4, H – 2, O – 1, S – 1, O - 2

22. Balancing Equations Sulfur is not balanced.
Place a two in front of sulfuric acid.
Count atoms: 2 H2SO4 H – 4, S – 2, O - 8
Cu + 2H2SO4
CuSO H2O + SO2

23. Balancing Equations
Hydrogen needs to be balanced so place a 2 in front of the H2O.
Count the number of atoms.
Cu + 2H2SO4
CuSO H2O + SO2

24. Balancing Equations Cu + 2H2SO4 CuSO4 + 2H2O + SO2
Reactants: Cu – 1, H – 4, S – 2, O – 8
Products: Cu – 1, S – 1, O – 4, H – 4, O – 2, S – 1, O – 2 = Cu – 1, S – 2, H – 4, O – 8
It’s balanced!
Cu + 2H2SO4
CuSO H2O + SO2

25. Balancing Equations
This method of balancing equations is the inspection method.
The method is trial and error.
Practice.