Chem Chapter 4

© Maya and Tara Balakrishnan 2009 Chemistry Chapter 4 Soluble: NO3-; C2H3O2Cl-; Br-; I- except with Ag+; Hg22+; Pb2+ SO42- except with Sr2+; Ba2+; Hg22+; Pb2+ Insoluble: S2- except with NH4+, the alkali metals, and Ca2+; Sr2+; Ba2+ CO32-; PO43-; except with NH4+, the alkali metals OH- except with the alkali metals, and Ca2+; Sr2+; Ba2+ Strong Acids: HCl; HBr; Hi; HNO3; H2SO4; HClO4; HClO3 Strong Bases: LiOH; NaOH; KOH; RbOH; CsOH; Ca(OH)2; Ba(OH)2; Sr(OH)2 Weak Bases: NH3 • • • •

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Strong electrolytes dissociate completely so the conduct electricity Substances that don’t ionize (molecules don’t break into ions) in solutions are nonelectrolytes Precipitation reactions produce a precipitate (insoluble solid) o Pb(NO3)2 (aq) + 2KI (aq)  PBI2 (s) + 2KNO3 (aq) Exchange/Metathesis Reactions (can also be a precipitation reaction) o AX + BY  AY + BX o AgNO3 (aq) + KCl(aq)  AgCl (s) +KNO3 (aq) In a net ionic equation, spectator ions are not written Acids ionize in aqueous solutions to form hydrogen ions, increasing their concentration Molecules of different acids can ionize to form different numbers of H+ ions o HCl and HNO3 are monoprotic acids o H2SO4 is a diprotic acid Bases accept H+ ions and produce OH- ions when dissolved in water Strong acids and strong bases are strong electrolytes Acid-Base Reaction/Neutralization Reaction and salts – neutralization rxn between an acid and metal hydroxide produces water and a salt o HCl (aq) + NaOH (aq)  H2O (l) + NaCl (aq) o Net ionic equation is H+(aq) + OH-(aq)  H2O(l) Acid-base rxn’s with gas formation

© Maya and Tara Balakrishnan 2009

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o 2HCl(aq) + Na2S(aq)  H2S(g) + 2NaCl(aq) o net ionic eq: 2H+(aq) + S2-(aq)  H2S(g) carbonates and bicarbonates react with acids to form CO2 gas oxidation-reduction reactions (redox): loss of electrons = oxidization; gain of electrons = reduction Oxidation numbers help keep track of electrons (make sure none go missing!) o Atoms in elemental form have an oxidation number of 0 o Monoatomic ions: the charge on the ion o Oxygen is usually -2 except when it’s peroxide o Hydrogen is +1 when bonded to nonmetals and -1 when bonded to metals o Fluorine is -1 in all compounds. Other halogens are -1 in most binary compounds but with H, they are positive o The sum of oxidation numbers in a neutral compound is 0 Displacement reactions o A + BX  AX + B o Can only work if A is above B in the activity series! Molarity (M) = moles solute/volume solution (L) Molarity of an ion in a compound is the molarity of the compound times the amount of that ion in the compound Moles solute (in concentrated sol.) × Volume (concentrated sol.) = Moles solute (in diluted sol.) × Volume (diluted sol.) Titration is combining a solution of known concentration (standard solution) with a solution of unknown concentration to find the unknown concentration The point where the stoichiometrically equal quantities are brought together is the equivalence point (usually the end of the reaction) and can be found with an indicator