1. Quiz Identify Type: 2H2O2 (l)  2 H2O (l) + O2 (g)
Combustion, Synthesis Reaction, Decomposition reaction, Single replacement, Double replacement
Identify Type: 2H2O2 (l)  2 H2O (l) + O2 (g)
Identify Type: SiO2 (l) + 2C (s)  Si (l) + 2CO (g)
Does this reaction take place? Al2(SO4) Fe  Fe2(SO4) Al
List all spectator ions in the following equation. Ba(NO3)2(aq)+2NaSO4(aq) BaSO4(s)+2 NaNO3(aq)

2. Quiz Identify Type: 2H2O2 (l)  2 H2O (l) + O2 (g)
Combustion, Synthesis Reaction, Decomposition reaction, Single replacement, Double replacement
Identify Type: 2H2O2 (l)  2 H2O (l) + O2 (g)
Identify Type: SiO2 (l) + 2C (s)  Si (l) + 2CO (g)
Does this reaction take place? Fe2(SO4) Al  Al2(SO4) Fe
List all spectator ions in the following equation. Ba(NO3)2(aq)+2NaSO4(aq) BaSO4(s)+2 NaNO3(aq)

3. 5.3 Redox reaction

4. The charge of an ion are also known as oxidation numbers
What is an ion?
Any charged atoms or molecules
How do you become ‘charged’?
By losing or gaining electrons
What is a cation? Did it lose or gain electrons?
Positive ion, it LOST electrons
What is an anion? Did it lose or gain electrons?
Negative ion, it GAINED electrons
The charge of an ion are also known as oxidation numbers

5. More Practice
If a metal iron, Fe, becomes an ion, Fe3+, how many electrons did it lose or gain?
It lost 3 electrons
If a pure sulfur, S, becomes an ion, S2-, how many electrons did it lose or gain?
It gained 2 electrons

6. Rules to find oxidation numbers
Neutral elements and diatomic molecules have an oxidation number of zero. Ex. Na, Fe, H2, O2, F2
Monatomic ions have oxidation number equal to its charge. Ex, Na+ is 1, O2- is -2. Do you know how to use P.T to find oxidation #?
Oxidation numbers in polyatomic ions add up to the total charge of the ion. Ex: shown NS

7. Example Sulfate is a polyatomic ion, with the formula of SO42-
The oxidation number of sulfur and four oxygen must add up to -2
Since oxygen is -2, the total negative charge of it is -8 (-2 * 4)
Sulfur must have an oxidation number of +6, to balance the oxygen, for the ion to have a charge of -2

8. (cations first, anions second)
What are the oxidation number of the elements in a nitrate ion?
NO3-
Oxygen is -2
Nitrogen is 5

9. Redox Reactions We have covered 5 major types of chemical reactions
Redox reaction is a totally different way to classify reactions, which can encompass all of the 5 major reactions
As long as reactants and products are exchanging electrons, it is called a redox reaction

10. CuSO4(aq) + Zn  Cu + ZnSO4(aq)
Copper(II) sulfate (CuSO4)is blue, zinc(II) sulfate (ZnSO4)is clear
This is a redox reaction because copper is exchanging electrons with zinc

11. Copper sulfate (CuSO4) dissolves in water to form two ions, copper (II) ion and sulfate ion
Cu2+ and SO42-
How do we know copper is +2?
Because we memorized sulfate(SO42-) a charge of -2, and so copper (II) ion needs to be +2 to make CuSO4 neutral
A roman numeral in parentheses represents the charge, and are needed for ALL transitional metal ions!

12. The zinc metal gives the copper (II) ion (Cu2+) two electrons
The zinc metal now becomes zinc (II) ion (Zn2+) while copper (II) ion (Cu2+) becomes copper metal (Cu) by gaining the two electrons
Reminder: electrons are negatively charged!

13. When zinc lost the electrons (gave it away), the reaction, Zn Zn2+ + 2e-, is called oxidation reaction
When copper (II) ion gained the electrons, the reaction, Cu2+ + 2e-  Cu, is called reduction reaction
Oxidation and reduction reaction happens at the same time, which we call redox reaction

14. Cu e-  Cu
Copper (II) ion Copper
Copper (II) ion was reduced (gained e-)

15. Zn  Zn e-
Zinc zinc (II) ion
Zinc was oxidized (lost e-)

16. LEO the lion says GER
Loss of Electrons is Oxidation
Gaining Electrons is Reduction
OIL RIG
mOre positive (Oxi)
lEss positive (rEduc)

17. Aluminium LOST 3 electrons. Which one is the correct equation?
A) Al + 3e-  Al3+
Al  Al3+ + 3e-
Is this Oxidation or Reduction?

18. Identify reduction and oxidation reaction
AgNO3(aq)  Cu → CuNO3(aq)  Ag
Ag+ NO Cu+ NO3-
Silver (I) ion Copper (I) ion
Ag+ gained, so reduction. Less positive.
Cu lost, so oxidation. More positive

19. Identify reduction and oxidation reaction
2 Na + FeCl2 → NaCl Fe
Fe Cl- Na+ Cl-
iron (II) ion sodium ion
Reduction: Iron, gained e-, less positive
Oxidation: Sodium, lost e-, more positive