AP Chemistry Unit 4: Solubility Rules and Polyatomic Ions

Polyatomic Ions; Strong Acids and Bases; and Solubility Rules to memorize

Solubility: Alkali Metals

All compounds containing alkali metals are soluble. This includes lithium, sodium, potassium, rubidium, cesium, and francium.

Solubility: Ammonium (NH₄⁺)

All compounds containing ammonium are soluble.

Solubility: Acetate (C₂H₃O₂⁻)

All compounds containing acetate are soluble.

Solubility: Chlorate/Perchlorate (ClO₃^-/ClO₄^-)

All compounds containing chlorate (ClO₃^-) or perchlorate (ClO₄^-) are soluble.

Solubility: Nitrate (NO₃^-)

All compounds containing nitrate (NO₃^-) are soluble.

Solubility: Halides

All ions in group 7A, or Column 17 of the periodic table (Cl-, Br-, I-) are soluble, except when paired with silver (Ag+), lead (Hg+), or mercury (Pb+).

Solubility: Sulfate (SO₄^2-)

Generally soluble, except when combined with barium (Ba2+), silver (Ag+), lead (Pb+), mercury (Hg+) strontium (Sr2+), lead (Pb2+), or calcium (Ca2+).

Strong Acids

HCl, HBr, HI, HNO₃, H₂SO₄, HClO₄

Strong Bases

Li(OH), Ca(OH)₂, Na(OH), K(OH), Sr(OH)₂, Ba(OH)₂

Ammonium

NH₄+

Acetate

C₂H₃O₂⁻

Bicarbonate or Hydrogen Carbonate

HCO3−

Perchlorate

ClO4-

Chlorate

ClO3-

Chlorite

ClO2-

Hypochlorite

ClO-

Cyanide

CN-

Hydroxide

OH-

Nitrate

NO_3^-

Nitrite

NO₂-

Permanganate

MnO₄-

Carbonate

CO₃^2-

Chromate

CrO₄^2-

Dichromate

Cr₂O₇^2-

Sulfate

SO₄^2-

Sulfite

SO₃^-2

Phosphate

PO₄^-3

Phosphite

PO₃^3-

Acid Naming Rules: Binary

Consists of H and another element, usually a halogen. Acid name begins with prefix “hydro-” followed by the name of anion, followed by the suffix “-ic.”

Acid Naming: Oxyacids

Consists of H, O, and a third element. Often contains polyatomic ions. If polyatomic ion ends with “-ite”, acid name ends with “ous.” If polyatomic ion ends with “-ate”, ends with “-ic.” Full written name is (Base name of the polyatomic) (-ous/-ic ) acid. Two examples are H2SO2 which contains sulfite written as Sufurous acid and H3PO4, which contains Phosphate being named phosphoric acid.

Base Naming

Written just like ionic compounds