Topic: Reactions in Aqueous Solution Do Now: Pick up 2 tests. Add correct answers to your test

Formation of a precipitate 2 aqueous solutions mixing to produce a solid

Reactions in aqueous solution Many reactions, esp. many double replacement reactions, occur in water. What happens when substances dissolve in water? Depends on if they are ionic or covalent.

Dissolving an Ionic Substance in a Water Ionc Dissolution (IONS) Example: NaCl(s)  Na + (aq) + Cl - (aq) CaCl 2 (s)  Ca 2+ (aq) + 2Cl - (aq) AlCl 3 (s)  Al 3+ (aq) + 3Cl - (aq) The ions are spread out among the water molecules.

Dissolving a Covalent Substance in water Molecular Dissolution (molecules) Ex: glucose C 6 H 12 O 6 (s)  C 6 H 12 O 6 (aq) The sugar molecules are spread out among the water molecules.

Not everything dissolves in water Soluble = dissolves in water Insoluble = doesn’t dissolve in water Miscible = 2 liquids that dissolve Immiscible = 2 liquids that don’t dissolve

How can you tell….?!!!?? Like Dissolve Like – Water is polar, so most polar compounds will dissolve in water All ionic compounds are polar – Use table F to see if it will dissolve in water Covalent compound – Polar will dissolve in water – Nonpolar will not dissolve in water NP (LOOK AT MOLECULAR SHAPE!) – Diatomic – Nobel gas – Pure hydrocarbon – Small symmetrical

Double Replacement Reactions Often occur when you mix 2 solutions of ionic compounds. – 1 product may be water or – 1 product may be a gas or – 1 product may be a solid We say these reactions “ go to completion. ”

Reactions producing Solids Precipitation: the opposite of dissolving! What do you see in the following clips: -TIGER VIDEOS

Reactions producing Solids p. 1 in your packet

Complete Ionic Equations 2K +1 (aq) + CrO 4 -2 (aq) + Ba 2+ (aq) + 2NO 3 -1 (aq)  2K + (aq) + 2NO 3 -1 (aq) + BaCrO 4 (s) Ionic substances that dissolve are written as ions in solution!

Net Ionic Equations 2K +1 (aq) + CrO 4 -2 (aq) + Ba 2+ (aq) + 2NO 3 -1 (aq)  2K + (aq) + 2NO 3 -1 (aq) + BaCrO 4 (s) Notice that some ions do not participate in the reaction. They are spectator ions. Cross out all the spectator ions & you get the net ionic equation. CrO 4 +2 (aq)+ Ba 2+ (aq)  BaCrO 4 (s)

Reactions that form Water HBr(aq) + NaOH(aq)  H 2 O(l) + NaBr(aq) H + (aq) + Br - (aq) + Na + (aq) + OH - (aq)  H 2 O(l) + Na + (aq) + Br - (aq) H + (aq) + OH - (aq)  H 2 O(l)

Reactions that form Gases HCl(aq) + NaHCO 3 (aq)  H 2 O(l) + CO 2 (g) + NaCl(aq) H + (aq) + Cl - (aq) + Na + (aq) + HCO 3 - (aq)  H 2 O(l) + CO 2 (g) + Na + (aq) + Cl - (aq) H + (aq) + HCO 3 - (aq)  H 2 O(l) + CO 2 (g)

Conservation of Charge Total charge on reactant side must equal total charge on product side. Mass of reactants = mass of products Total # Atoms of reactants = Total # Atoms of products Conservation of Mass