1. Catalyst
Write the net ionic equation for the following double replacement reactions. Predict the precipitate the forms.
Silver nitrate and sodium chloride are mixed
Lead nitrate and potassium iodide are mixed
Lithium hydroxide and Iron (III) chloride are mixed
End

2. Redox Reactions!

3. Lecture 3.3 – Redox Reactions and Writing Chemical Equations

4. Today’s Learning Targets
LT 3.4 – I can hypothesize about the product(s) that would form from the reaction between two or more reactants and write the net ionic equation for the reaction. Furthermore, I can hypothesize when a reaction will not occur.
LT 3.5 – I can determine the oxidation numbers for all elements and molecules that participate in an oxidation-reduction reaction.

5. Oxidation – Reduction Reactions
Oxidation-Reduction reactions (or redox reactions) are reactions that involve the transfer of electrons from one element to another element
A substance either gives or receives electrons

6. LEO the lion says GER
Lose
Electrons
Oxidized
Gain
Electrons
Reduced

7. Assigning Oxidation Numbers
In order to identify substances that are gaining or losing electrons, we assign oxidation numbers.
An atoms in element form have a state of 0
A monoatomic ions oxidation number equals its charge (e.g. K+ = +1 oxidation number). This also applies to monoatomic ionic compounds.
Non-metals have the charge of their group usually:
Oxygen is always -2 except in peroxides (O22-) where it is -1
Hydrogen is usually +1 when bonded to nonmetals and -1 when bonded to metals
Halogens almost always are -1. Fluorine is always -1, all other halogens may have a positive charge
The sum of the oxidation numbers in a compound equal the charge of the compound.

8. Class Example
Assign the oxidation numbers to SCl2

9. Table Talk
Assign the oxidation number to the following compound P2O5

10. 2 Al (s) + 6 HBr (aq)  2 AlBr3 (aq) + 3 H2 (g)
Class Example
Assign the oxidation states to the following elements/compounds and identify the substances being oxidized and reduced:
2 Al (s) + 6 HBr (aq)  2 AlBr3 (aq) + 3 H2 (g)

11. Mg (s) + CoSO4 (aq)  MgSO4 (aq) + Co (s)
Table Talk
Assign the oxidation states to the following elements/compounds and identify the substances being oxidized and reduced:
Mg (s) + CoSO4 (aq)  MgSO4 (aq) + Co (s)

12. Activity Series
We can predict the reactivity of metals when mixed together by using an activity series.
An activity series is a list of metal arranged from most likely to go through oxidation to least likely to go through oxidation.
Ones at the bottom likely to be reduced when ran in reverse.
Also, can be used to predict whether a redox reaction will occur

13. Handout 3.3.Activity Series

14. Handout 3.3.Activity Series

15. Class Example
Will an aqueous solution of iron (II) chloride oxidize magnesium metal?
Magnesium is located higher on the periodic table than iron, so it will go from Mg (s) to Mg2+ and iron chloride will go in reverse from Fe2+ to Fe (s)

16. Table Talk
Will a solution of Pb(NO3)2 oxidize solid zinc?
Yes, P

17. Fun with Post – Its! Around the room there are 4 problems.
You have 4 Post – Its. Label the oxidation of states of all compounds/elements and identified substances being oxidized or reduced
Mg (s) + CO2 (s)  2MgO (s) + C (s)
2C6H6 + 15O2  12CO2 + 6H2O
5C2H42- + MnO4– +16H+  2Mn CO2 + 8H2O
Cu + 2Ag+  2Ag + Cu2+

18. FRQ Question 4
3 reactions will be given. Reactants stated, you must predict products.
In all cases, a reaction occurs
The equations must be balanced
Equations must be written in net ionic form – spectator ions eliminated from the final answer
Descriptive question after each reaction

19. Six Types of AP Reactions
1. Double Replacement -Precipitation Reactions -Acid/Base Reactions 2. Redox Reactions 3. Decomposition/Synthesis Reactions/Combustion 4. Organic Reactions 5. Complex Ion Formation 6. Lewis Acid Bases
Most Common

20. Acid-Base Reactions: How to Identify
Know your strong acids and bases!
If you are able to identify both reactants as acids and/or bases, then predicting the products becomes easy!
Acids and bases always react to form salts and water

21. Strong Acid/Strong Base Reactions
If both products are a strong acid/strong base reaction, then you can use the following rules.
A strong acid and strong base reaction always produces water in the net ionic equation:
H+ + OH–  H2O

22. Strong Acid/Base and Weak Acid/Base Reaction
If only one of the two compounds is a strong acid/base and the other is a weak acid/base, then the final reaction looks different
The weak acid/base only partially dissociates, so the net ionic contains the acid/base in both forms:
CH3COOH + OH-  CH3COO- + H2O
Example

23. Acid/Base and Oxides
A metal oxide or non-metal oxide are when compounds bind to oxygen.
These oxides act as acids and bases
Double replacement reaction with water and salt formation
Final product is not soluble in water

24. Class Example
Hydrobromic acid and calcium hydroxide are mixed

25. Table Talk
Acetic acid (CH3COOH) and potassium hydroxide are mixed

26. Precipitation Reactions
Solid formation can be seen in all reactions
Knowing your precipitation rules will allow for you to predict whether a solid will form
Solubility Rules
Compounds with these, usually soluble
-NH4+
-NO3-
-Na+
-K+
-CH3COO-
-ClO3-
Compounds with these, usually insoluble
-O-2
-OH-
-CO3-2
-PO4-3
-S-2

27. Class Example Cobalt chloride and sodium carbonate are mixed
Mix these chemicals together and have students oberve

28. Table Talk
Aqueous barium chloride and aqueous potassium sulfate are mixed

29. Redox Reactions: How to Identify
There are certain chemicals that always undergo redox reactions:
The presence of these substances indicates a redox reaction is going to occur.
Use the activity series to predict the products!
Strong Oxdizers
Strong Reducers
Cr2O72-
MnO4-
H2O O3
Halogens
Group I ions
Group II ions
Reduced Chemicals
Oxidized Chemicals

30. Class Example
A bar of strontium metal is immersed in a 1.0 M copper (II) nitrate solution.

31. Table Talk
An aqueous solution of iron (II) chloride is mixed with magnesium metal.

32. Combustion Reactions Recall, a combustion reaction is:
Hydrocarbon + O2  H2O + CO2
We will learn how to name the hydrocarbons at the end of the year. You will be given the molecule until then.

33. Decomposition Reactions
When given only one compound and statement like “compound is heated”, this is a decomposition reaction.
The most common decomposition reactions are:
1. metal carbonates  carbon dioxide + metal oxide
MCO3  CO2 + MO
2.metal hydrogen carbonates  carbon dioxide + metal carbonate + water
MHCO3  CO2 + MCO3 + H2O
3. metal halates  oxygen + metal halide
MClO3  O2 + MCl
4.metal sulfites  sulfur dioxide + metal oxide
MSO3  SO2 + MO
5. hydrogen peroxide  oxygen + water
H2O2  O2 + H2O

34. Other Important Information
CO3 will break down to CO2 when in a reaction
ALWAYS answer the questions. You can always get at least one point
Solids and gases do not have spectator ions

35. Writing Reactions Problem Set
With the remaining time, complete the Problem Set 3.3 – Writing Chemical Reactions
In all cases, a reaction occurs
You must write the net ionic equation.

37. Closing Time Problem Set 3.3 Homework 3.3 due Tuesday/Wednesday
Net Ionic Equation lab write-up due Thursday/Friday