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 Balancing hints: Balance the metals first.
Balance the ion groups next.
Balance the other atoms.
Save the non ion group oxygen and hydrogen until the end.

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

27. Writing and Naming Nickel + hydrochloric acid
Nickel(II) chloride + hydrogen
Write the corresponding formula equation and then balance the equation.

28. Writing and Naming Ni + HCl NiCl2 + H2 Ni + 2HCl NiCl2 + H2
Write each formula independently.
Ignore the rest of the equation.
Balance the equation after writing the formulas.
Ni + HCl NiCl2 + H2
Ni + 2HCl NiCl2 + H2

29. Writing and Naming
Remember the diatomic elements: H2, N2, O2, F2, Cl2, Br2, and I2.

30. Writing and Naming Cu + H2SO4 CuSO4 + H2O + SO2
Balance the formula equation.
Write the word equation.

31. Writing and Naming Cu + 2H2SO4 CuSO4 + 2H2O + SO2 Write the names:
Cu by itself is just copper. Copper(I) or copper(II) would be incorrect.
H2SO4 should be named as an acid.
Sulfuric acid

32. Writing and Naming
CuSO4 has a SO42- group so Cu must be 2+. Some metals must have Roman Numerals. Copper(II) sulfate
H2O is known as water.
SO2 is a nonmetal compound. Its name is either sulfur dioxide or sulfur(IV) oxide.

33. Writing and Naming Cu + 2H2SO4 CuSO4 + 2H2O + SO2
Copper + sulfuric acid 
Copper(II) sulfate + water + sulfur dioxide

34. Balancing Equations
Chapter 8
Practice!