Writing correct chemical equations requires that you know how to predict products of reactions. Even with limited experience, one can use a few guidelines to accomplish this. Seven frequently used elements naturally occurring as diatomic molecules: H₂. O₂, N₂, Cl₂, Br₂, I₂. This is how they should always be written in a chemical equation. Ionic species are in aqueous solution, (aq); States of matter should be included by (s),(l),(g) after the chemical symbol.

GENERAL CLASSIFICATIONS OF REACTIONS

SOLUBILITY RULES:

SOLUBLE:

All Nitrates, Acetates, Ammonium and Group I salts

All Chlorides, Bromides, and Iodides, except Silver, Lead & Mercury(I)

All Fluorides except Group II, Lead(II), and Iron(III)

All Sulfates except Calcium, Strontium, Barium, Mercury, Lead(II), and Ag.

INSOLUBLE:

All Carbonates & Phosphates except Group I and Ammonium(NH4+)

All Hydroxides except Group I, Sr, Ba

All Sulfides except Group I,II, and NH4+

All Oxides except Group I

INSOLUBLE means a precipitate forms when equal volumes of 0.10 M solutions or greater are mixed