1. Chapter 4 (4.1-4.5) Reactions in aqueous solution
Electrolytes vs. nonelectrolytes
Molecular & ionic equations
Precipitation reactions (solubility)
Acid/base reactions
Oxidation/reduction reactions
Concentration of solutions

2. A solution is a homogenous mixture of 2 or more substances
The solute is(are) the substance(s) present in the smaller amount(s)
The solvent is the substance present in the larger amount
Solution
Solvent
Solute
Soft drink (l)
H2O
Sugar, CO2
Air (g) N2
O2, Ar, CH4
Soft Solder (s) Pb Sn

3. An electrolyte is a substance that, when dissolved in water, results in a solution that can conduct electricity.
A nonelectrolyte is a substance that, when dissolved, results in a solution that does not conduct electricity.
nonelectrolyte
weak electrolyte
strong electrolyte

4. Cations (+) and Anions (-) conduct electricity in solution
Strong Electrolyte – 100% dissociation
NaCl (s) Na+ (aq) + Cl- (aq)
H2O
Weak Electrolyte – not completely dissociated
CH3COOH CH3COO- (aq) + H+ (aq)

5. Ionization of acetic acid
CH3COOH CH3COO- (aq) + H+ (aq)
A reversible reaction. The reaction can occur in both directions.
Acetic acid is a weak electrolyte because its ionization in water is incomplete.

6. Nonelectrolytes do not conduct electricity
No cations (+) and anions (-) in solution
C6H12O6 (s) C6H12O6 (aq)
H2O

7. So how do you know if it is a strong, weak, or non-electrolyte?
Molecular compounds are non.
Ionic compounds are strong or weak.
ALL insoluble cpds are weak.
MOST soluble cpds are strong.
Memorize exceptions.
Some acids and bases
H2O
NH3
And more that I won’t ask you to memorize

8. General solubility rules for salts
Soluble
All nitrates (NO3-), bicarbonates (HCO3-) and chlorates (ClO3-)
All acetates (C2H3O2- or CH3COO-) except Ag+
All halides (Cl-, Br-, I-) except Ag+, Pb2+, Hg22+
All sulfates (SO42-) except Ag+, Ca2+, Sr2+, Ba2+, Pb2+, Hg22+
All alkali metal ion (Na+, K+, Rb+, Li+, Cs+), NH4+ salts
All common inorganic acids
Insoluble
All hydroxides (OH-) except alkali metal ions, NH4+, Ba2+
All chromates (CrO4-), carbonates (CO32-), phosphates (PO43-), and oxalates (C2O42-) except alkali metals and NH4+
All sulfides (S2-) except Na+, K+, NH4+, Mg2+, Ca2+, Ba2+

9. Some common strong electrolytes
Acids
HCl
HNO3
H2SO4
HClO4
Bases
NaOH
KOH
Ba(OH)2
Etc
Salts
all soluble salts with a few exceptions, see below.
Some common weak electrolytes
HC2H3O2 HF
HNO2
H3PO4
H2C2O4
H2SO3
H2CO3
H2S
NH3
Mg(OH)2
Ca(OH)2
Fe(OH)3
etc
Salts/other
HgCl2
Pb(C2H3O2)2
H2O

10. Three types of reactions in aqueous solution (in this chapter)
Precipitation reactions
Acid/base reactions
Oxidation/reduction reactions

11. Precipitation Reactions
Precipitate – insoluble solid that separates from solution
precipitate
Pb(NO3)2 (aq) + 2NaI (aq) PbI2 (s) + 2NaNO3 (aq)
molecular equation
Pb2+ + 2NO3- + 2Na+ + 2I PbI2 (s) + 2Na+ + 2NO3-
ionic equation
Pb2+ + 2I PbI2 (s)
net ionic equation
Na+ and NO3- are spectator ions

12. Writing Net Ionic Equations
Write the balanced molecular equation.
Write the ionic equation showing the strong electrolytes completely dissociated into cations and anions. Do NOT dissociate weak electrolytes.
Cancel the spectator ions on both sides of the ionic equation
AgNO3 (aq) + NaCl (aq) AgCl (s) + NaNO3 (aq)
Ag+ + NO3- + Na+ + Cl AgCl (s) + Na+ + NO3-
Ag+ + Cl AgCl (s)

13. Three types of reactions in aqueous solution (in this chapter)
Precipitation reactions
Acid/base reactions
Oxidation/reduction reactions

14. Arrhenius acid is a substance that produces H+ (H3O+) in water
Hydronium ion
Arrhenius base is a substance that produces OH- in water

15. A Brønsted acid must contain at least one ionizable proton!
A Brønsted acid is a proton donor
A Brønsted base is a proton acceptor
base
acid
acid
base
A Brønsted acid must contain at least one ionizable proton!

16. CH3COO- (aq) + H+ (aq) CH3COOH (aq) Brønsted base
Identify each of the following species as a Brønsted acid, base, or both. (a) HI, (b) CH3COO-, (c) H2PO4-
HI (aq) H+ (aq) + I- (aq)
Brønsted acid
CH3COO- (aq) + H+ (aq) CH3COOH (aq)
Brønsted base
H2PO4- (aq) H+ (aq) + HPO42- (aq)
Brønsted acid
H2PO4- (aq) + H+ (aq) H3PO4 (aq)
Brønsted base

17. Monoprotic acids Diprotic acids Triprotic acids HCl H+ + Cl-
Strong electrolyte, strong acid
HNO H+ + NO3-
Strong electrolyte, strong acid
CH3COOH H+ + CH3COO-
Weak electrolyte, weak acid
Diprotic acids
H2SO H+ + HSO4-
Strong electrolyte, strong acid
HSO H+ + SO42-
Weak electrolyte, weak acid
Triprotic acids
H3PO H+ + H2PO4-
Weak electrolyte, weak acid
H2PO H+ + HPO42-
Weak electrolyte, weak acid
HPO H+ + PO43-
Weak electrolyte, weak acid