1. Types of Chemical Reactions and Solution Stoichiometry
Chapter 4
Types of Chemical Reactions and Solution Stoichiometry

2. Water (H2O = HOH) Solvent - dissolves solute to make solutions
Aqueous means dissolved in water
Water dissolves many substances
Water’s molecular shape: bent d+ d-
H2O

3. Water’s polarity
Causes ionic compounds to “fall apart” in water when opposite charges become attracted to one another
Called hydration
Some molecules are more soluble in water than others

4. Electrical Conductivity
A solution’s ability to conduct electricity
The more ions in a solution, the stronger the electric current will be
Pure water does NOT conduct electricity

5. Electrolytes
STRONG electrolytes: solutions that conduct electric current very efficiently
WEAK electrolytes: solutions that conduct a small electric current
NONelectrolytes: solutions that permit no current flow

6. NaCl (s) Na+ (aq) + Cl- (aq)
Strong Electrolytes
100% Dissociation (breaking apart)
Many ions are created in aqueous solution
Examples: soluble salts, strong acids, strong bases
NaCl (s) Na+ (aq) + Cl- (aq)
H2O

7. HA(aq) + H2O(l) --> H3O+(aq) + A-(aq)
Arrhenius Acid
Substance that produces H+ ions (protons) when dissolved in water
Proton donor
HA(aq) + H2O(l) --> H3O+(aq) + A-(aq)
Like irrelevant

8. STRONG Acids HCl: hydrochloric acid - produces H+ and Cl-
HNO3: nitric acid - produces H+ and NO3-
H2SO4: sulfuric acid - produces H+ and HSO4-
Not in book - HBr (hydrobromic acid), HI (hydroiodic acid), HClO4 (perchloric acid)
Characteristics: sour taste (vinegar, citrus fruits), cause color changes in plant dyes, pH is low (0-7)

9. Arrhenius Bases
Substance that produces a hydroxide (OH-) ion when dissolved in water
Like irrelevant

10. STRONG Bases NaOH: sodium hydroxide - produces Na+ and OH-
KOH: potassium hydroxide - produces K+ and OH-
Not in book: LiOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2 (you probably won’t see these)
Characteristics: bitter taste, feel slippery (soaps usually contain bases), cause color changes in plant dyes, pH is high (7-14)
Group I/II hydroxides

11. CH3COOH CH3COO- (aq) + H+ (aq)
Weak Electrolyte
Doesn’t completely dissociate in water
Relatively few ions are produced when dissolved in water
Weak acids/bases
A reversible reaction can occur in both directions
CH3COOH CH3COO- (aq) + H+ (aq)

12. Nonelectrolytes Create almost no ions when dissolved in water
Ex: sucrose C12H22O11

13. Molarity A unit representing concentration Unit is moles per liter
M = moles of solute
liters of solution
Read as “____ molar”

14. Molarity Example Grams need to be converted to moles
mL need to be converted to L
How many mL of solution are necessary if we are to have 2.48 M NaOH solution that contains g of the dissolved solid?
Answer: 318 mL solution
See book pg

15. More on Molarity…
Multiply molarity by number of ions in the solution to find molarity of specific ions:
Calculate the molarity of all the ions in the following:
0.25 M Ca(OCl)2
Anwer: 0.25 M Ca2+, 0.50 M OCl-
2 M CrCl3
Answer: 2 M Cr3+, 6 M Cl-

16. Dilution
We can add water to solutions and consequently water them down (dilute) them. *only the amount of water changes, not the solvent!
M1V1 = M2V2
M = molarity
V = volume (units must match for 1 and 2)

17. Dilution Example
What volume of 12 M hydrochloric acid must be used to prepare 600 mL of a 0.30 M HCl solution?
Answer: L = 15 mL of 12 M HCl

18. Types of Reactions: Review!
Combination/Synthesis
Decomposition
Single Replacement
Double Replacement
Combustion
*NEW: Acid-Base Reactions
*NEW: Oxidation-Reduction Reactions

19. Combination/Synthesis
One product!
Two elements = combine and balance charges 2Al + 3O2 --> 2Al2O3
Nonmetal oxide + water produces an acid CO2 + H2O --> H2CO3

20. Decomposition One reactant Breaks into its element (diatomics!)
2MgO --> 2Mg + O2
Metal carbonate --> metal oxide + CO2
Na2CO3 --> Na2O + CO2
Metal chlorate --> metal chloride + O2
2 Al(ClO3)3  2 AlCl3 + 9 O2
more…

21. 2Al(s) + 3Pb(NO3)2(aq)  3Pb(s) + 2Al(NO3)3(aq)
Single Replacement
Lone metal (nonmetal) + compound
Metals (or nonmetals) switch
CHECK ACTIVITY SERIES - lone metal must be higher or NR
2Al(s) + 3Pb(NO3)2(aq)  3Pb(s) + 2Al(NO3)3(aq)

22. Double Replacement Two compounds’ metals switch spots
MUST bubble, form a molecule like water or form a precipitate (precipitate reaction)
USE SOLUBILITY RULES!

23. Solubility Rules Slightly soluble = Insoluble and means (s)
Soluble means (aq)
MUST BE MEMORIZED!!

24. Acronyms for Solubility
CASHN Gia
C = chlorates, A = acetates, S = sulfates, H = halogens, N = nitrates, and Gia = group 1 A metals (all soluble)…EXCEPT…
For sulfates = Ca, Ba, Sr (remember CBS like TV), Happy-whats happy? Hg Ag Pb…mercury, silver and lead…add a -py to the end and all the first letters spell "happy”
For halogens: only the Happy part
If it’s not part of CASHN Gia, it’s insoluble.
SONG?? Or this one…another…

25. Predict Products/Precipitates
KCl(aq) + Pb(NO3)2(aq) ->
2KCl(aq) + Pb(NO3)2(aq) -> PbCl2(s) + 2KNO3(aq)
AgNO3(aq) + MgBr2(aq) ->
2AgNO3(aq) + MgBr2(aq) -> 2AgBr(s) + Mg(NO3)2(aq)
Ca(OH)2(aq) + FeCl3(aq) ->
3Ca(OH)2(aq) + 2FeCl3(aq) -> 2Fe(OH)3(s) + 3CaCl2(aq)
NaOH(aq) + HCl(aq) ->
NaOH(aq) + HCl(aq) -> H2O(l) + NaCl(aq)

26. Combustion Organic compound (CHO) + O2 --> CO2 + H2O
Usually releases energy (light or heat)

27. ***NOTE!
It is assumed from now on that if a reaction isn’t written out you can (and will) write it out…