1. CHEMICAL REACTIONS Chapter 4
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Reactants: Zn + I2
Product: Zn I2

2. 4 Al(s) + 3 O2(g) ---> 2 Al2O3(s)
Chemical Equations
4 Al(s) O2(g) ---> 2 Al2O3(s)
This equation means
4 Al atoms + 3 O2 molecules >
2 formula units of Al2O3
4 moles of Al + 3 moles of O >
2 moles of Al2O3

3. Chemical Equations stoichiometric coefficients
Depict the kind of reactants and products and their relative amounts in a reaction.
4 Al(s) O2(g) ---> 2 Al2O3(s)
The numbers in the front are called
stoichiometric coefficients
The letters (s), (g), and (l) are the physical states of compounds.

4. It must have the same number of atoms of the same kind on both sides.
Lavoisier, 1788
Chemical Equations
Because of the principle of the conservation of matter,
an equation must be balanced.
It must have the same number of atoms of the same kind on both sides.

5. The Law of the Conservation of Matter
Chemical Equations
The Law of the Conservation of Matter
The amount of matter in a system does not change: the same atoms are present in a reaction at the beginning and at the end.

6. Balancing Equations
___ Al(s) + ___ Br2(liq) ---> ___ Al2Br6(s)

7. Balancing Equations
____C3H8(g) _____ O2(g) > _____CO2(g) _____ H2O(g)
____B4H10(g) _____ O2(g) > ___ B2O3(g) _____ H2O(g)

8. STOICHIOMETRY
- the study of the quantitative aspects of chemical reactions.

9. STOICHIOMETRY It rests on the principle of the conservation of matter.
2 Al(s) Br2(liq) > Al2Br6(s)

10. STOICHIOMETRY CALCULATIONS
Stoichiometric
factor
Moles
product
Moles
reactant

11. 1. How many moles of acid are need to react all the zinc?
Zn + HCl ð ZnCl2+ H2 2
Given 7 mol of Zn,
1. How many moles of acid are
need to react all the zinc?
2. How many moles of hydrogen
gas are produced?
3.How many moles of ZnCl2 are
produced?

12. KClO3 ð KCl O2 2 3 2
Given you need to produce 21 moles of oxygen gas:
1. How many moles of KClO3 do you need to start with?
2. How many moles of KCl are produced?

13. 2 7 4 6 __C2H6+ O2 ð CO2+ H2O Given 10 moles of C2H6 :
1. How many mole of oxygen gas do you need to react all the ethane?
2. How many moles of water are produced?
3. How many moles of carbon dioxide will be produced?