1. Predicting amounts of reagents needed or amounts of products made
Stoichiometry
Predicting amounts of reagents needed or amounts of products made

2. 2 C2H6 + 7 O2  4 CO2 + 6 H2O Stoichiometry problems:
How much CO2 will be produced if 4 moles of C2H6 are consumed?
Stoichiometry problems:
1) Start with balanced chemical equation
2) Problem will ask how many moles/liters given yield certain amount of something else

3. 4 X 2 C2H6 + 7 O2  4 CO2 + 6 H2O 4 moles C2H6 X moles CO2 ___________
How much CO2 will be produced if 4 moles of C2H6 are consumed?
4 moles C2H6
X moles CO2
___________
___________ =
2 moles C2H6
4 moles CO2
X = 8 moles CO2

4. 5 X 2 C2H6 + 7 O2  4 CO2 + 6 H2O 5 moles C2H6 X moles H2O
How much H2O will be produced in the combustion of 5 moles of C2H6?
5 moles C2H6
X moles H2O
____________ =
___________
2 moles C2H6
6 moles H2O
X = 15 moles H2O

5. 5 X 2 C2H6 + 7 O2  4 CO2 + 6 H2O 5 moles C2H6 X moles O2 =
How much oxygen will react with 5 moles of C2H6?
5 moles C2H6
X moles O2 =
___________
___________
2 moles C2H6
7 moles O2
X = 17.5 moles O2

6. Coefficients in Balanced Equations
Give relative number of particles in rxn
Give relative number of moles in rxn
Coefficients give relationship between moles of each component in equation
You use these relationships in MOLE-MOLE problems to convert from moles of 1 substance to moles of another substance

8. Volume/Volume
Word Problems
Involving Gases

9. Gas-Phase Equations
1 mole of any gas occupies the same volume as any other gas (At STP, 22.4 L/mol)
coefficients in equations represent the
ratio of the volumes of gases involved in rxn
rxns where ALL reactants & products are gases
 volume-volume problems
Unit doesn’t matter as long as it’s constant throughout

10. N2(g) H2(g)  2 NH3(g)
How much hydrogen gas will react with 15 liters of nitrogen gas?
15 L N2(g)
X L H2(g)
_________
_________ =
1 L N2(g)
3 L H2(g)
X = 45 L H2(g)

12. A word about ….

13. Single Replacement Reactions
A + BX  AX + B
Element + Compound 
New Element + New Compound

14. Single Replacement Rxns
2 Li(s) + 2 H2O(l)  2 LiOH(aq) + H2(g)
In this reaction, a metal replaces a hydrogen in a water molecule

15. Single Replacement Rxns
Another common type is when one metal replaces another metal in a compound
Cu(s) AgNO3(aq) 
2 Ag(s) + Cu(NO3)2(aq)

16. Single Replacement Reactions
Metals have different reactivities
You have to predict if a given metal and a given compound will react or not

17. Single Replacement Rxns
Table J is an activity series
The more reactive a metal, the easier it loses its valence electrons
The most active metal is at the top
The least active metal is at the bottom
Use Table J to determine if a reaction will occur

18. Single Replacement Rxns
The rule is:
A metal can replace any metal listed below it on table J
It cannot replace any metal listed above it on table J

19. Ag(s) + Cu(NO3)2(aq)  ? What is the metal and the metal cation?
Ag and Cu+2
Locate Ag and Cu in Table J
Ag is below Cu so this reaction will not go
Ag is less reactive than Cu

20. Cu(s) + 2 AgNO3(aq)  ? What is the metal and the metal cation?
Cu and Ag+1
Locate Cu and Ag in Table J
Cu is above Ag in Table J
Cu is more reactive than Ag
This reaction will go
 2 Ag(s) + Cu(NO3)2(aq)

21. Single Replacement Reactions
3rd common type:
A nonmetal replaces another nonmetal in a compound
Halogens are often the nonmetal
Halogens also have different reactivities
Look at Table J
Most active halogen = fluorine at top
Least active halogen = iodine at bottom

22. Single Replacement Reactions
The rule is:
A more active halogen replaces a less active halogen that is part of a compound in aqueous solution
F2(g) NaBr(aq)  2 NaF(aq) + Br2(l)
This reaction occurs because F2 is above Br2

23. Single Replacement ReactionNR
Br2(g) NaF(aq)  ?
Br2 is below F2 in Table J
This reaction does not occur

24. Use Table J to predict if these reactions occur
K(s) + ZnCl2(aq) 
Fe(s) + Na3PO4(aq) 
Cu(s) + Mg(NO3)2(aq) 
Al(s) + SnCl2(aq) 
Ca(s) + KBr(aq) 
Ti(s) + Pb(NO3)2(aq) 
Cl2(g) + HF(aq) 
F2(g) + CaI2(aq) 
Yes No No
Yes No
Yes No
Yes

26. Double
Replacement
Reactions

27. Reactions in aqueous solution
Many reactions, esp. many double replacement reactions, occur in water
What happens when substances dissolve in water?
Depends on if they are ionic or covalent

28. Dissolving Covalent substance – sugar or C6H12O6
C6H12O6(s)  C6H12O6(aq)
The sugar molecules are spread out among the water molecules

29. Dissolving Ionic substance – table salt or NaCl
NaCl(s)  Na+1(aq) + Cl-1(aq)
The ions are spread out among the water molecules

30. Double Replacement Reactions
Often occur when you mix 2 solutions of ionic compounds
1 product may be water or
1 product may be a gas
1 product may be a solid

31. Reactions producing Solids
Precipitation: the opposite of dissolving!

32. Reactions producing Solids
2 NaOH(aq) + CuCl2(aq) 
2 NaCl(aq) + Cu(OH)2(s)
Chemical Equation

33. Complete Ionic Equations
2Na+1(aq) + 2OH-1(aq) + Cu2+(aq) + 2Cl-1(aq) 
2Na+1(aq) + 2Cl-1(aq) + Cu(OH)2(s)
Substances that are ions in solution are written as ions in solution = aqueous

34. Net Ionic Equations 2Na+1(aq) + 2OH-1(aq) + Cu2+(aq) + 2Cl-1(aq) 
2Na+1(aq) + 2Cl-1(aq) + Cu(OH)2(s)
Notice that some ions do not participate in the reaction
They are spectator ions
Cross out all the spectator ions & you get the net ionic equation
2OH-1(aq) + Cu2+(aq)  Cu(OH)2(s)

35. Reactions that form Water
HBr(aq) + NaOH(aq)  H2O(l) + NaBr(aq)
H+1(aq) + Br-1(aq) + Na+1(aq) + OH-1(aq) 
H2O(l) + Na+1(aq) + Br-1(aq)
H+1(aq) + OH-1(aq)  H2O(l)

36. Reactions that form Gases
HCl(aq) + NaHCO3(aq)  H2CO3(aq) + NaCl(aq)
H2CO3(aq)  H2O(l) + CO2(g)
______________________________________
HCl(aq) + NaHCO3(aq) 
H2O(l) + CO2(g) + NaCl(aq)

37. Reactions that form Gases
HCl(aq) + NaHCO3(aq) 
H2O(l) + CO2(g) + NaCl(aq)
H+1(aq) + Cl-1(aq) + Na+1(aq) + HCO3-1(aq) 
H2O(l) + CO2(g) + Na+1(aq) + Cl-1(aq)
H+1(aq) + HCO3-1(aq)  H2O(l) + CO2(g)

38. Conservation of Charge
Total charge on reactant side must equal total charge on product side