SALT
-compounds with metal cations or ammonium cation (NH₄⁺¹), and nonmetal anions or polyatomic anions.
Examples: MgBr₂, K₂SO₄, NH₄NO₃

ACID
-a compound that increases the concentration of hydrogen ions (H⁺¹) when dissolved in water.
-any species that can donate a proton (H⁺¹).
-acids formulas are often written with the donatable proton at the beginning of the formula.
Examples: HCl, H₂SO₃, HC₇H₅O₂

BASE
-a compound that increases the concentration of hydroxide ions (OH^-1) when dissolved in water.
-any species that can accept a proton (H⁺¹).
-base formulas are written with the hydroxide ion at the end of the formula.
Examples: NaOH, Ca(OH)₂, Al(OH)₃

ELECTROLYTES AND NONELECTROLYTES

Electrolyte
- compounds that conduct electricity when dissolved in water.

Two types of electrolytes
    1. Strong: most of the solute is in the form of ions.
            a. Soluble salts: NaCl, KNO₃, (NH₄)₂CO₃
            b. Strong acids: HCl, HBr, HI, HNO₃, HClO₄, H₂SO₄
            c. Strong bases: Group I hydroxides, and Ca(OH)₂, Sr(OH)₂, Ba(OH)₂
    2. Weak: most of the solute is in the form of molecules.
            a. Weak acids: HC₂H₃O₂, H₂C₂O₄
            b. Weak bases: NH₃ (ammonia)

Soluble salts are strong electrolytes because they dissociate in aqueous solution.
    NaCl(s) + H₂O(l) ---> NaCl(aq)
    or
    NaCl(s) + H₂O(l) ---> Na^+l(aq) + Cl^-1(aq)

Strong acids are strong electrolytes because they dissociate in aqueous solution.
HBr(g) + H₂O(l) ---> H^+l(aq) + Br^-1(aq)

Strong bases are strong electrolytes because they dissociate in aqueous solution.
KOH(s) + H₂O(l) ---> K^+l(aq) + OH^-1(aq)

Weak acids and weak bases do not appreciably dissociate enough to conduct electricity.
HC₂H₃O₂(aq) + H₂O(l) <===> H^+l(aq) + C₂H₃O₂^-1(aq)

Nonelectrolyte
-a solution of a compound that does not conduct an observable amount of electricity.
    A sugar such as glucose is an example of a compound which will dissolve in water but
    will not conduct electricty.
        C₆H₁₂O₆(s) + H₂O(l) ---> C₆H₁₂O₆(aq)

ACID-BASE REACTIONS (Neutralizations)
Acids and bases can be defined in two general ways:
1) Arrhenius acids and bases
2) Bronsted and Lowry acids and bases.

Arrhenius Acids and Bases
An acid is a substance that produces hydrogen ions, H⁺, when it dissolves in water.
HNO₃ + H₂O ---> H⁺ + NO₃^-

A base is a substance that produces hydroxide ions, OH^-1, when it dissolves in water.
NH₃ + H₂O ---> NH₄¹⁺ + OH^1-

Bronsted and Lowry Acids and Bases
An acid is the species (molecule or ion) that donates a proton to another species in a proton-tranfser reaction.

A base is the species (molecule or ion) that accepts a proton in a proton-transfer reaction.

NH₃ + H₂O ---> NH₄¹⁺ + OH^1-
Base Acid

HNO₃ + H₂O ---> NO₃^1- + H₃O¹⁺
Acid Base

HNO₃ + NH₃ ---> NH₄¹⁺ + NO₃^1-
Acid Base

STRONG AND WEAK ACIDS
There are only 6 strong acids.
HCl, HBr, HI, H₂SO₄, HNO₃, HClO₄

Strong acids ionize completely and are strong electrolytes.
HBr(g) + H₂O(l) ---> H^+l(aq) + Br^-1(aq)

Weak acids ionize partly in water and are weak electrolytes.
HC₂H₃O₂(l) + H₂O(l) <===> H^+l(aq) + C₂H₃O₂^-1(aq)

STRONG AND WEAK BASES
There are only 8 strong bases.
LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)₂, Sr(OH)₂, Ba(OH)₂

Strong bases ionize completely and are strong electrolytes.
KOH(s) + H₂O(l) ---> K^+l(aq) + OH^-1(aq)

Weak bases ionize partly in water and are weak electrolytes.
NH₃(g) + H₂O(l) <===> NH₄^+l(aq) + OH^-1(aq)

NEUTRALIZATION REACTIONS
Acids react with hydroxide bases to yield a salt and water.

Acid + Base ---> Salt + Water

HClO₄(aq) + LiOH(aq) ---> LiClO₄(aq) + H₂O(l)

H₂SO₄(aq) + 2 NaOH(aq) ---> Na₂SO₄(aq) + 2 H₂O(l)

HI(aq) + KOH(aq) ---> KI(aq) + H₂O(l)

HBr(aq) + Ca(OH)₂(aq) ---> CaBr₂(aq) + 2 H₂O(l)

HCl(aq) + Sr(OH)₂(aq) ---> SrCl₂(aq) + 2 H₂O(l)

HNO₃(aq) + Ba(OH)₂(aq) ---> Ba(NO₃)₂(aq) + 2 H₂O(l)

MOLECULAR AND IONIC EQUATIONS

Molecular Equation: Shows compounds as if they exist in solution in the form of molecules.

Pb(NO₃)₂(aq) + Na₂SO₄(aq) --> PbSO₄(s) + 2 NaNO₃(aq)

Complete Ionic Equation: shows soluble ionic compounds(i.e. soluble salts) as ions
in solutions and molecules are shown as molecules in solution.

Pb²⁺(aq) + 2 NO₃^1-(aq) + 2 Na¹⁺(aq) + SO₄^2-(aq) --> PbSO₄(s) + 2 Na¹⁺(aq) + 2 NO₃(aq)

Net Ionic Equation: shows only the species that take part in a reaction.

Pb²⁺(aq) + SO₄^2-(aq) --> PbSO₄(s)

Spectator Ions: ions which do not take part in a reaction and remain the same.
They appear in the same form and state on either side of the equation.
In the example cited above the sodium cation [Na¹⁺(aq)] and the nitrate anion [NO₃^1-(aq)]
are spectator ions.

EXAMPLE
Show the molecular, complete ionic and net ionic equations from the mixing of an aqueous solution of
ammonium carbonate [(NH₄)₂CO₃(aq) ]and calcium chloride [CaCl₂(aq)].

Molecular Equation:

(NH₄)₂CO₃(aq) + CaCl₂(aq) ---> 2 NH₄Cl(aq) + CaCO₃(s)

Complete Ionic Equation:

2 NH₄¹⁺(aq) + CO₃^2-(aq) + Ca²⁺(aq) + 2 Cl^1-(aq) ---> 2 NH₄¹⁺(aq) + 2 Cl^1-(aq) + CaCO₃(s)

Net Ionic Equation:

Ca²⁺(aq) + CO₃^2-(aq) ---> CaCO₃(s)

A precipitate is an insoluble solid compound formed during a chemical reaction in solution.
CaCO₃(s), AgCl(s), BaSO₄(s) [The (s) indicates insoluble solid.]

SOLUBILITY RULES FOR IONIC COMPOUNDS

Rule       Statement                                                                    Exceptions
1            Group IA [Li¹⁺,Na¹⁺,K¹⁺] and ammonium                      NONE
              compounds [NH₄¹⁺] are soluble.

2 Acetates[ C₂H₃O₂^1-] & nitrates [NO₃^1-] are soluble. NONE

3             Most chlorides, bromides, and iodides                              AgCl, Hg₂Cl₂, PbCl₂,
                [Cl^1-, Br^1-, I^1- ] are soluble.                                            AgBr, HgBr, Hg₂Br₂, PbBr₂,
                                                                                                     AgI, HgI₂, Hg₂I₂, PbI₂

4 Most sulfates [SO₄^2-] are soluble. CaSO₄, SrSO₄, BaSO₄,
Ag₂SO₄, Hg₂SO₄, PbSO₄

5 Most carbonates [CO₃^2-] are insoluble. Group IA carbonates, (NH₄)₂CO₃

6 Most phosphates [PO₄^3-] are insoluble. Group IA phosphates, (NH₄)₃PO₄

7 Most sulfides [S^2-] are insoluble. Group IA sulfides, (NH₄)₂S

8 Most hydroxides [OH^1-] are insoluble. Group IA hydroxides, Ca(OH)₂,
Sr(OH)₂, Ba(OH)₂

An exchange or Metathesis Reaction
-a reaction between compounds that, when written as a molecular equation, appears to involve
the exchange of parts between the two reactants.
-reactions between ion in solution that form insoluble and weak or nonelectrolytes.

Predicting Reactions:
When solutions of electrolytes are mixed, a reaction will take place if one or both of the possible
products is either insoluble or a weak or nonelectrolyte.

Reactions are basically rearrangements of atoms. Therefore swap cation and anions to see
what could be possible products. If either of the products are insoluble or weak or nonelectrolytes,
then a reaction takes place.

SAMPLE PROBLEMS

1) BaCl₂(aq) + ZnSO₄(aq) ---> ?
    BaCl₂(aq) + ZnSO₄(aq) ---> BaSO₄(s) + ZnCl₂(aq)
    BaSO₄ is an insoluble solid (precipitate) therefore a reaction takes place when aqueous solutions
    of BaCl₂ and ZnSO₄ are mixed together.

2) Na₂S(aq) + ZnCl₂(aq) ---> ?
    Na₂S(aq) + ZnCl₂(aq) ---> NaCl(aq) + ZnS(s)
    ZnS is an insoluble solid (precipitate) therefore a reaction takes place when aqueous solutions of
    Na₂S and ZnCl are mixed together.

3) K₃PO₄(aq) + NaNO₃(aq) ?
    K₃PO₄(aq) + NaNO₃(aq) ---> KNO₃(aq) + Na₃PO₄(aq)
    K₃PO₄(aq) + NaNO₃(aq) ---> NO REACTION
    All of the proposed products are soluble, therefore a reaction does not take place when aqueous
    solutions of K₃PO₄ and NaNO₃ are mixed.

REVIEW OF PRECIPITATION RXNS
Reactions are basically rearrangements of atoms. Therefore swap cations and anions to see what could be possible products. If either of the products are insoluble or weak or nonelectrolytes, then a reaction takes place.