1. Chapter 10
Chemical Reactions

2. Balancing Chemical Equations
Steps for Balancing Equations
Write the skeleton equation
Use arrows, +/- & physical states of matter
2. Count the atoms of the reactants
3. Count the atoms of the products
4. Change the coefficients to make the number of atoms of each element equal on both sides of the equation
 NEVER, NEVER CHANGE THE SUBSCRIPT
5. Write the coefficients in their lowest possible ratio

3. Count the reactants & products
Balance the H & O atoms with coefficients for the reactants to = the products

4. Add the physical states of the elements Now you have a happy equation
YOU'RE NOT DONE !!
Add the physical states of the elements
Now you have a happy equation

5. Types of Reactions Synthesis Reaction General form A + B  AB
A chemical reaction in which 2 or more reactants produce 1 product
General form A + B  AB
In the cartoon, the skinny bird (reactant) and the worm (reactant) combine
to make one product, a fat bird.

6. Synthesis Reaction Examples 2Na + Cl2  2NaCL 2Mg + O2  2MgO
4Al + 3O2  2Al2O3
H20 + SO3  H2SO4 (this is one cause of acid rain)
H20 +CO2  H2CO3 (this is why rainwater is naturally acidic)
H2O + MgO  Mg(OH)2

7. Synthesis (combin.) Reaction
Special CASE “Scenarios” for these RXN’s
Metallic oxide + Water  Base
Na2O + H2O  2NaOH
Non-Metallic oxide + Water  Acid
SO3 + H2O  H2SO4

8. Synthesis (combin.) Reaction
Special CASE “Scenarios” for these RXN’s
Metallic oxide + CO2  Metal carbonate
CaO + CO2  CaCO3
Metal chloride + Oxygen  Metal chlorate
2KCl + 3O  2KClO3

9. Decomposition Reaction
A chemical reaction where 1 compound, breaks apart into 2 or more simpler products
General form AB  A + B
In this cartoon the egg (the reactant), which contained the turtle at one time, now has opened and the turtle (product) and egg shell (product) are now two separate substances.

10. Decomposition reactions often require an energy source:
Examples
2 H2O  2H2 + O2
2HgO  2Hg + O2
2Ag2O  4Ag + O2
CaCO3  CaO + CO2
H2CO3  H2O + CO2
Decomposition reactions often require an energy source:
Heat
Light
Electricity

11. Decomposition Reaction
Special CASE “Scenarios” for these RXN’s
Heating an acid  non metallic oxide + water
Heating a base  metallic oxide + water
Heating a carbonate  oxide + CO2
Heating a metal chlorate  chloride + O2
Heating a metallic oxide  Metal + O2
Heating a sulfite  Metal oxide + SO2
These are just the reverse of their synthesis RXN’s

12. Single Replacement Reaction
A reaction in which atoms of one element replace the atoms of another element that is part of a compound
Notice, the guy in the orange shirt steals the date of the other guy. So, a part of one of the reactants trades places and is in a different place among the products

13. Single Replacement Reaction
1. Cations replace Cations
General Form AB + C  CB + A
C would be the cation/metal and so replaced A, which would have to be a cation
2. Anions replace Anions
General Form DE + F  DF + E
F would be the anion/non-metal and so replaced E, which would have to be a anion

14. Single Replacement Reaction
Examples:
Cu + AgNO3  Cu(NO3)2 + Ag
Cation replaces Cation
NaI + Cl2  NaCl + I2
Anion replaces Anion

15. Special situations for SR RXN’s
Single Replacement Reaction
Special situations for SR RXN’s
1. Activity Series
Definition 
A list of metal/cations in order of decreasing reactivity
Used to determine if one metal can replace another in a RXN
The higher its position on chart the more metals it can replace
Ex: sodium will replace aluminum
The lower its position on the chart the less metals it can replace
Ex: zinc will not replace magnesium

16. Special situations for SR RXN’s
Single Replacement Reaction
Special situations for SR RXN’s
Water  for writing RXN’s it may be useful to write water
as H(OH). Why?
Halogens
The halogens also have a series;
As you go down group 17 they decrease in reactivity
Ex: Chlorine cannot replace fluorine but it can replace bromine

17. Single Replacement Reaction
Special situations for SR RXN’s
Do the following reactions occur? Explain.
Zn + H2SO4  H2 + ZnSO4
Sn + 2NaNO3  Sn(NO3) Na
2NaCl + F2  2NaF + Cl2
CaCl2 + I2  CaI2 + Cl2

18. Double Replacement Reaction
A reaction where there is an exchange of cations between 2 ionic compounds
Notice how the first guy exchanged hats with the second guy, so they are both wearing each other's hat.

19. Double Replacement Reaction
General Form
AB + CD  AD + CB
** Make sure of cation and anion placement
Ex:
BaCl2 + K2CO3  BaCO3 + 2KCl
3KOH + H3PO4  3H(OH) + K3PO4

20. Double Replacement Reaction
“Driving Forces” allow a RXN to take place
Use your net ionic equation to see if one of the following are formed
“Driving Forces” in double replacement RXN’s
One of three things must form for these RXN’s to occur
1. A molecular compound like water forms
A gas forms that bubbles out i.e.
(H2, CO2, H2S, CO, etc.)
3. A precipitate forms

21. Double Replacement Reaction
How do you know if something is a precipitate?
1. It is insoluble or slightly soluble in water
2. Check your solubility chart
Examples: will these RXN’s occur? Explain
BaCl2
Soluble….NR
AgCl
Insoluble….Yes
Ca3(PO4)2
Insoluble….Yes
NaNO3
Soluble….NR

22. Double Replacement Reaction
Examples: will these RXN’s occur?
FeS(s) + HCl(aq)  FeCl2(aq) + H2S ↑
Yes
Pb(NO3)2 (aq) + 2KI (aq)  2KNO3 (aq) + PbI2 ↓
Yes
FeCl3 (aq) + Al(NO3)3 (aq)  Fe(NO3)3 (aq) + AlCl3 (aq)
No…soluble …
no “driving force” present

23. Combustion Reactions Definition:
Oxygen reacts with another substance often producing energy in the form of heat and light
General form: CxHy + O2  CO2 + H2O
Types:
1. Complete combustion
Definition:
If sufficient oxygen is present to burn completely
Hydrocarbons combine with oxygen to produce
carbon dioxide and water

24. Combustion Reactions 2. Incomplete combustion Definition:
Insufficient oxygen is present to burn completely
Hydrocarbons combine with oxygen to produce poisonous carbon monoxide and solid elemental carbon as well as carbon dioxide and water
Examples:

25. Extra “Special” RXN’s Reactive metals and water (SR)
Group 1 and 2 metals react to form a metal hydroxide and hydrogen gas
Acid and a Base
React to form a salt (ionic compound composed of the anion of the acid and the cation of the base) and water

26. Aqueous SLN
When two (aq) solutions that contain ions as solutes combine….
The ions may react with one another
The H20 molecules don’t usually react
The three types of products can form aka “driving forces” …. Gas, water, or precip
Chemical equations do not always show all that happens in a RXN

27. Net Ionic Equations Solutions are composed of Solute Solvent
Aqueous SLN
Is a sln in which the solvent is water

28. Net Ionic Equations
Substances that are ions in a solution and are written as such
These equations show all of the particles in a solution as they “really” exist
Some ions are in both the RXT & PROD, these are called…
SPECTATOR IONS

29. Net Ionic Equations
SPECTATOR IONS - dissociation only occurs if it is in an aqueous solution
S, L, G are not ions see your solubility chart

30. Net Ionic Equations Regular equation
2NaOH (aq) + CuCl2 (aq)  2NaCl (aq) + Cu(OH)2(s)
Ionic equation
2Na+ (aq) + 2OH- (aq) + Cu+2(aq) + 2Cl- (aq)  2Na+(aq) + 2Cl- (aq) + Cu(OH)2 (s)

31. Net Ionic Equations Net Ionic equation
2OH- (aq) + Cu+2(aq)  Cu(OH)2 (s)
Net ionic equation is formed when all of the spectator ions are cancelled