1. Part 4: Balancing Equations
Science 10 Review
Part 4: Balancing Equations

2. Balancing Chemical Equations
Study Guide p. 110
Balancing Chemical Equations

3. Balancing Chemical Equations
Count the number of each atom on reactant and product side of equation (multiply coefficient and subscript).
Study Guide p. 110

4. ___Al(s) + ___I2(g)  ___AlI3(s)
Study Guide p. 110
Balancing Chemical Equations
___Al(s) + ___I2(g)  ___AlI3(s)

5. ___Al(s) + _3_I2(g)  ___AlI3(s)
Study Guide p. 110
Balancing Chemical Equations
___Al(s) + _3_I2(g)  ___AlI3(s)

6. ___Al(s) + _3_I2(g)  _2_AlI3(s)
Study Guide p. 110
Balancing Chemical Equations
___Al(s) + _3_I2(g)  _2_AlI3(s)

7. _2_Al(s) + _3_I2(g)  _2_AlI3(s)
Study Guide p. 110
Balancing Chemical Equations
_2_Al(s) + _3_I2(g)  _2_AlI3(s)

8. Always double check your answer.
Study Guide p. 110
Step 4
Always double check your answer.
e.g. __Al(s) + __ I2(g)  __ AlI3(s) 2 3 2
Products
Al = 2
I = 6
Reactants
Al = 2
I = 6

9. Balance elements in elemental form (Fe, O2, S8, P4) last.
Study Guide p. 110
Helpful Hints:
Balance elements in elemental form (Fe, O2, S8, P4) last.

10. Balance elements in elemental form (Fe, O2, S8, P4) last.
Study Guide p. 110
Helpful Hints:
Balance elements in elemental form (Fe, O2, S8, P4) last.
Balance polyatomic ions (e.g. SO42-) as a group if they don’t break apart.

11. Balance elements in elemental form (Fe, O2, S8, P4) last.
Study Guide p. 110
Helpful Hints:
Balance elements in elemental form (Fe, O2, S8, P4) last.
Balance polyatomic ions (e.g. SO42-) as a group if they don’t break apart.
Balance oxygen and hydrogen last.

12. Example: 25 Oxygen __C8H18(s) + __ O2(g)  __ CO2(g) + __ H2O(g) 8 9
12.5 8 9
25 Oxygen
16 Oxygen
9 Oxygen
25 Oxygen +