Acids, bases and salt preparations

General solubility rules for ionic compounds

Sodium, potassium, and ammonium compounds are soluble; all nitrates are soluble.

Solubility of common chlorides

Most chlorides are soluble, except silver chloride (AgCl) and lead(II) chloride (PbCl₂).

Solubility of common sulfates

Most sulfates are soluble, except barium sulfate (BaSO₄), calcium sulfate (CaSO₄), and lead(II) sulfate (PbSO₄).

Solubility of common carbonates

Most carbonates are insoluble, except sodium carbonate (Na₂CO₃), potassium carbonate (K₂CO₃), and ammonium carbonate ((NH₄)₂CO₃).

Solubility of common hydroxides

Most hydroxides are insoluble, except sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH)₂ slightly soluble).

Acids and bases in terms of proton transfer

Acids are proton donors (give H⁺ ions); bases are proton acceptors (take H⁺ ions).

Acid-base theory

Acids release H⁺ ions in solution; bases accept H⁺ ions or release OH⁻ ions.

Reactions of acids with metals

Acid + metal → salt + hydrogen gas; reaction depends on reactivity of metal.

Reactions of acids with bases

Acid + base → salt + water; neutralisation reaction.

Reactions of acids with metal carbonates

Acid + metal carbonate → salt + water + carbon dioxide.

What is a base?

Metal oxides, metal hydroxides, or ammonia that can neutralise acids; alkalis are soluble bases.

Preparing a soluble salt from an insoluble reactant

1. Gently heat acid. 2. Add insoluble reactant (metal oxide or carbonate) until in excess. 3. Filter to remove unreacted solid. 4. Evaporate filtrate to form saturated solution. 5. Cool to crystallise. 6. Filter and dry crystals.

Preparing a soluble salt from an acid and alkali

Use titration to neutralise exact volume; evaporate solution to crystallise; filter and dry crystals.

Preparing an insoluble salt from two soluble reactants

Mix aqueous solutions; precipitate forms; filter, wash, and dry precipitate to get pure salt.

Preparing hydrated copper(II) sulfate crystals

Heat copper(II) oxide with sulfuric acid until in excess; filter, evaporate solution, allow to crystallise, then dry.

Preparing lead(II) sulfate

Mix soluble lead(II) nitrate with sodium sulfate; precipitate forms; filter, wash, and dry to get pure PbSO₄.