1. Types of Reactions

2. Updated types of reactions…
Regular Chemistry
AP Chemistry
Synthesis
Decomposition
Single Replacement
Double Replacement
Combustion
Precipitation Reactions
Acid-Base Reactions: involves electrolytes & neutralization
Redox Reactions = most reactions are redox!
Double replacement = metathesis reactions (many precipitation & acid-base reactions)
Updated types of reactions…

3. Anatomy of an AP Chemistry Test
Reactions

4. AP Chemistry Exam; Part 2B Free response
How to earn points on writing reactions:
AP Chemistry Exam; Part 2B Free response

5. Calcium metal is added to water
Job #1: classify, recognize common reactions
Job #2 Predict products
Metals + water produce insoluble hydroxides and hydrogen gas
1 of 3 points possible
Ca + H20 
3 of 3 points possible
Ca + H20  Ca(OH) 2 + H2
2 of 3 points possible
Ca + H20  Ca+2 +OH- + H2
Ca+2  Ca OH- + H2
1 of 3 points possible
Ca(aq)  Ca OH- + H+
0 of 3 points possible

6. Precipitation Reactions
When one mixes ions that form compounds that are insoluble (as could be predicted by the solubility guidelines), a precipitate is formed.

7. Metathesis (Exchange) Reactions
Metathesis comes from a Greek word that means “to transpose”
AgNO3 (aq) + KCl (aq)  AgCl (s) + KNO3 (aq)

8. Metathesis (Exchange) Reactions
Metathesis comes from a Greek word that means “to transpose”
It appears the ions in the reactant compounds exchange, or transpose, ions
AgNO3 (aq) + KCl (aq)  AgCl (s) + KNO3 (aq)

9. Metathesis (Exchange) Reactions
Metathesis comes from a Greek word that means “to transpose”
It appears the ions in the reactant compounds exchange, or transpose, ions
AgNO3 (aq) + KCl (aq)  AgCl (s) + KNO3 (aq)

10. Ag+(aq) + Cl-(aq)  AgCl (s)
Net Ionic Equation
To form the net ionic equation, cross out anything that does not change from the left side of the equation to the right.
The only things left in the equation are those things that change (i.e., react) during the course of the reaction.
Ag+(aq) + Cl-(aq)  AgCl (s)

11. Displacement Reactions
In displacement reactions, ions oxidize an element.
The ions, then, are reduced.

12. Oxidation-Reduction Reactions
An oxidation occurs when an atom or ion loses electrons.
A reduction occurs when an atom or ion gains electrons.

13. Oxidation-Reduction Reactions
One cannot occur without the other.

14. Displacement Reactions
Copper is put into a solution of silver nitrate:
In this reaction,
silver ions oxidize
copper metal.
Cu (s) + 2 Ag+ (aq)  Cu2+ (aq) + 2 Ag (s)

15. Displacement Reactions
The reverse reaction,
however, does not
occur.
Cu2+ (aq) + 2 Ag (s)  Cu (s) + 2 Ag+ (aq) x

16. How many points? Cu + AgNO3  Ag + Cu(NO3)2
1 point for one correct product= Ag
Cu+2 + Ag+ + NO3-  Ag+ + Cu+2 + NO3-
1 point for one correct product= Cu+2
Cu + Ag+  Ag + Cu(NO3)2
2 points; one for correct reactants & one for correct product

17. Activity Series
Use activity series to predict metal displacement; halogen displacement

18. Gas-Forming Reactions
These metathesis reactions do not give the product expected.
The expected product decomposes to give a gaseous product (CO2 or SO2).
CaCO3 (s) + HCl (aq) CaCl2 (aq) + CO2 (g) + H2O (l)
NaHCO3 (aq) + HBr (aq) NaBr (aq) + CO2 (g) + H2O (l)
SrSO3 (s) + 2 HI (aq) SrI2 (aq) + SO2 (g) + H2O (l)

19. Gas-Forming Reactions
This reaction gives the predicted product, but you had better carry it out in the hood, or you will be very unpopular!
Just as in the previous examples, a gas is formed as a product of this reaction:
Na2S (aq) + H2SO4 (aq)  Na2SO4 (aq) + H2S (g)

20. Homework Classify reactions the old way
Synthesis (redox), decomposition (redox), single replacement (redox), double replacement (metathesis)
Predict & balance synthesis & decomposition reactions (7-2)
Use activity series to predict products in displacement reactions (8-1)