SCH3U/4C Ms. Richardson Chemistry in the Environment ACIDS & BASES SCH3U/4C Ms. Richardson Chemistry in the Environment

Common industrial acids & Bases Hydrochloric acid (HCl) – textiles, photography, food, rubber industries; mining Ammonia (NH3) – fertilizer, synthetic fibres, commercial explosives Phosphoric acid (H3PO4) – soft drinks, detergents, dentistry Lime (CaO) – agriculture, construction, scrubber technology Sulfuric acid (H2SO4) – electrolytes, medicines, explosives, dyes/paints, soaps; mining Sodium hydroxide (NaOH) – drain cleaner, soaps, plastic; oil refining, fracking

Properties of Acids And Bases Conduct the lab and summarise the properties of acids and bases.

Theories of Acids & Bases The Arrhenius Theory describes acids and bases based on how they behave in water. Acids ionize in water to produce one or more hydrogen ions. HCl(g)  H+(aq) + Cl -(aq) Bases dissociate in water to release one or more hydroxide ions. NaOH(g)  Na+(aq) + OH -(aq)

Problems with The Arrhenius Theory Arrhenius’ theory doesn’t work for all acids and bases. Consider ammonia, NH3 which doesn’t contain hydroxide but forms basic solutions when dissolved in water. NH3(g) + H2O(l) NH4+(aq) + OH-(aq)

Problems with Arrhenius Theory When acids ionize, the H+(aq) that form are attracted to water and react with the water to form H3O+(aq), known as the hydronium ion. H+(aq) + H2O(l)  H3O+ (aq)

The Modified Arrhenius Theory ACID: A substance that reacts with water to produce H3O+(aq) in aqueous solution. BASE: A substance that dissociates in water or reacts with water to produce OH-(aq) in aqueous solution.