1. Ch 11

2. Chapter 8 Balancing Equations and Law of Conservation of mass
What kind of reaction is it?
Will SR or DR occur?
Given eqn. as a sentence, write formula (visa versa)
Predict Products of all 5 reaction types (given type of reaction)
State s, l, g, or aq in a reaction equation

3. Common Terms to Know: Reacts with: And: Yield : Produces:
8.1 Chemical Equations Chemical equations represent, with symbols and formulas, the reactants and products in a chemical reaction.
Common Terms to Know:
Reacts with:
And:
Yield :
Produces:

4. Reminder
7 Diatomics?

5. Requirements for all chemical equations:
Must show all reactants and products
Formulas must be correct
Law of Conservation of Mass must be satisfied (equation must be balanced)

6. Nitrogen gas reacts with Oxygen gas to produce Nitrogen dioxide
H Cl2  2 HCl

7. 2NaCl(s)  2Na(s) + Cl2(g)
Ex1:– decomposition of sodium chloride – start from scratch – use symbols, heat, etc.
2NaCl(s)  2Na(s) + Cl2(g)
Ex2: NaCl(s) = solid sodium chloride NaCl(aq) = solution of sodium chloride (in water)
H2O(l) - liquid water (not aqueous - redundant)

8. ppt or ↓ = precipitate (solid - only found on products side)
other symbols to know:
 = one way reactions
↔ = reversible reaction
(g) or ↑ = gas
ΔH = heat
cat = catalyst (a substance that speeds up a reaction without being used up in the reaction)
ppt or ↓ = precipitate (solid - only found on products side)

9. White the equation for the following sentences
Potassium Chloride decomposes into potassium and Chlorine gas
Aluminum reacts with Chromium III oxide to form Chromium and Aluminum oxide.
Dicarbon hexahydride reacts with oxygen to form carbon dioxide and water.

10. More practice if necessary
Wks pkt 27-31

11. Wks pkt
Write the sentence for the following formulas 1 2 4 7

12. So, what does the chemical equation actually mean?? H2 + Cl2  2 HCl
In atoms:
2 atoms of hydrogen gas react with 2 atoms of chlorine gas to yield 2 atoms of hydrogen and 2 atoms of chlorine
In molecules:
1 molecule of hydrogen gas reacts with 1 molecule of chlorine gas to produce 2 molecules of hydrochloric acid
In molar mass:
H = 2.0g + Cl = 71.0g  HCl = 73.0

13. Why do chemical equations need to be balanced?

14. Balancing Chemical Equations A trial and error process
Balance 1 atom at a time
Balance atoms that appear only 1X per side first
Balance polyatomic ions as a whole unit
Balance diatomic elements last
Balance O and H last – if possible

15. 2
Ex:
___Mg
____O2 2 + 
____MgO
Mg | Mg 1
O | O 1
1) Balance 1 atom at a time
2) Balance atoms that appear only 1X per side first
3) Balance polyatomic ions as a whole unit
4) Balance diatomic elements last
5) Balance O and H last – if possible
If this doesn’t succeed, try doubling everything (particularly with combustion).
Try W.S. 8-1…

16. Exit Ticket

17. Exit Ticket
____Al2O3  ____Al ____O2

18. Warm Up Show Mr. Roberts your homework
Put 2 answers from the HW on the board

19. 8.2 Types of Chemical Reactions
There are 5 types of chemical reactions
Synthesis
Decomposition
Combustion
Single Replacement
Double Replacement
remember - first you’ve got to find the right products, then you balance

20. 1. Synthesis Needs energy to occur (usually heat)
General Formula: A + B  AB
Ba + S  Mg + Cl2 
Al + Cl2  Na + O2 
BaS
MgCl2
AlCl3
Na2O
2Al + 3Cl2  2AlCl3
4Na + O2  2Na2O

21. Go over CH 7 Test and recollect
Go over wks 3 synthesis

22. 2. Decomposition Needs energy to happen (heat or electricity)
General Formula: AB  A + B
FeCl3  HgO 
Fe + Cl2
Hg + O2
2FeCl3  2Fe + 3Cl2
2HgO  2Hg + O2

23. 3. Combustion The reaction of hydrocarbons and oxygen General Formula:
CxHy + O2  H2O + CO2
CH4 C3H8
C4H10 C2H5OH

24. How can you tell between the 3 rxns?
Synthesis
Decomposition
Combustion

25. What type of reaction is each?
2FeCl3  2Fe + 3Cl2
4Na + O2  2Na2O
C2H4 + O2  H2O + CO2

26. What type of reaction is each?
___FeCl3  ____________
___Na + ___O2  ______________
___C2H4 + ___O2 ______________

27. Worksheet 1 and 2 Label S, D or C
Worksheet 3 Decomposition
Worksheet 6 (1-10)

28. Act it out
Single Replacement (prom and +/-)
Double Replacement

29. 4. Single Replacement Takes place in aqueous solutions
Needs very little energy to happen
2 Types
Positive Ions Switch
General Formula: AB + M  MB + A
HI + Mg 
AlCl3 + Ca 
Ca + HOH  2
MgI2 + H2 3 2
3CaCl2 + 2Al 2
Ca(OH)2 + H2

30. General Formula: AB + X  AX + B
- Negative Ions Switch
General Formula: AB + X  AX + B
NaCl + F2 
BaS + O2 
NaF + Cl2
BaO + S

31. 5. Double Replacement FeCl3 + NaOH 
again - aqueous solution - little energy - usually forms one soluble ionic product (aka - aqueous) and either a ppt, water, or a gas that bubbles out of water
General Formula: AB + CD  CB + AD
FeCl3 + NaOH 
H2SO4 + NaOH 
NH4Cl + NaOH 

32. How can you tell them apart?
Single replacement
Double replacement

33. What type of reaction is each?
2FeCl3  2Fe + 3Cl2
FeCl3 + 3NaOH  Fe(OH) NaCl
4Na + O2  2Na2O
Ca HOH  Ca(OH)2 + H2
C2H4 + O2  H2O + CO2

34. Worksheet 1 and 2 label SR and DR

35. 8.3 Activity Series of the Elements
hey, some reactions happen and some don’t - for synthesis, combustion, and decomposition, we will assume they all happen given sufficient activation energy ( Ea )
Challenger must be more active (stronger) to replace
For single replacement, use the Activity Series!
Ca + H2O yields Al + H2O yields
Al + HI yields Cu + HI yields
NaCl + F2  NaF + Cl2 →

36. B.6 Metals – Properties and Uses
More Active
Less Active

37. Any single element above an element in a compound will replace it.
Rules for the single replacement activity series:
Any single element above an element in a compound will replace it.
The top 5 elements react with water.
Metals above H react with acids (molecules that start with H – not water).
The nonmetal reactivity series is F> Cl > Br >I

38. For double replacement reactions, use a Solubility Table!
Rules for double replacement reactions using a solubility table:
If one of the products formed is water, the reaction happens.
If a gas is formed, the reaction happens.
If an insoluble product forms (I or Ss), the reaction happens (actually a reaction may happen when two soluble products form, but it doesn’t go to completion and is not directly observable).

39. Na2CrO4 + KCl  NR (both products soluble)
FeCl3 + KOH  Fe(OH)3(ppt) KCl(aq)
Yes! The reaction happens!
Note: precipitate symbols include (ppt) and (s).
HCl + NaOH 

40. Complete wks 4 and 5

41. Showing Energy Changes in Equations
Endothermic – put in heat (left side of equation)
A + B + heat  C ΔH is positive
Exothermic – releases heat (right side)
- A + B  C + heat ΔH is negative

42. Some helpful notes on writing phases in chemical reactions
Metals are solids (except Hg)
In SR and DR reactions reactants that are compounds are always aqueous
In SR and DR reactions products that are compounds should have their phases identified using a solubility chart (aq. vs. ppt)
In S and D reactions ionic compounds are always solid
In C reactions, the water, CO2, and O2 are gases. The hydrocarbon is a gas but usually becomes a liquid at C=6 or higher
Most other covalent compounds are gases
Acids (chemicals starting with H) are aqueous

43. Heavier stuff doesn’t dissolve well
NIB Solubility Trends
Cations -very soluble - Na, K, ammonium
-very insoluble- Ag, Pb, Hg, transitions
Anions - very soluble - nitrate
for monatomics- F>Cl>Br ....
very insoluble - carbonate, hydroxide, phosphate, sulfate
sulfides - decompose
general trend - As size decreases, solubility increases OR
Heavier stuff doesn’t dissolve well

44. Put SR or DR on wks 1 and 2
Worksheet 6
Worksheet 7
HW bookwork problems due Wed 2/12
Pg 290 1, 7-13, 15, 18, 22-27, 30, 31, 34-36, 41-43, 47
LAB MONDAY- appropriate clothing!!!!!