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Determining if a compound is soluble (aq) or NOT. LOOK AT TABLE F LiOH Cu(NO 3 ) 2 AgCl 2 MgS NaS 2 KOH. aq aq insoluble = precipitate = s insoluble = precipitate = s aq aq. Double Replacement Reactions. Format : AX + BY AY + BX. Double Replacement.
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Determining if a compound is soluble (aq) or NOT • LOOK AT TABLE F • LiOH • Cu(NO3)2 • AgCl2 • MgS • NaS2 • KOH • aq • aq • insoluble = precipitate = s • insoluble = precipitate = s • aq • aq
Double Replacement Reactions
Format: AX + BY AY + BX Double Replacement
DR rns occur in aqueous solutions • So, what exactly happens to a substance when we put it in water? • depends if ionic or covalent
Dissolving Covalent substance – ex: sugar (C6H12O6) C6H12O6(s) C6H12O6(aq) • sugar molecules spread out among water molecules
Dissolving • Ionic substance – • ex: table salt (NaCl) • NaCl(s) Na+1(aq) + Cl-1(aq) • ions spread out among water molecules
Double Replacement Reactionsoccur with 2 ionic compound solutions • Products can be: - liquid (H2O) • - gas • - solid Reactions producing solids • Precipitation: • solid is formed - opposite of dissolving! MOVIE
This is the Chemical Equation but it’s not the whole story… EX: Reactions producing Solids 2 NaOH(aq) + CuCl2(aq) 2 NaCl(aq) + Cu(OH)2(s)
2 NaOH(aq) + CuCl2(aq) 2 NaCl(aq) + Cu(OH)2(s) In solution it’s not NaOH and CuCl2You actually have ions floating around in water • Reactants: 2Na+1(aq) + 2OH-1(aq) + Cu2+(aq) + 2Cl-1(aq) • Products: 2Na+1(aq) + 2Cl-1(aq) + Cu(OH)2(s) Cu2+ Na+1 Cu2+ Na+1 H H O H O H H O H O H H Cl+1 Cu2+ Cu O Na+1 O H H O H H H H O O Cu2+ H O Cl+1 Cu Cl-1 O H ions in solution are written as aqueous
Here’s what is really involved in the reaction… 2OH-1(aq) + Cu2+(aq) Cu(OH)2(s) 2 NaOH(aq) + CuCl2(aq) 2 NaCl(aq) + Cu(OH)2(s) Net Ionic Equations 2Na+1(aq) + 2OH-1(aq) + Cu2+(aq) + 2Cl-1(aq) 2Na+1(aq) + 2Cl-1(aq) + Cu(OH)2(s) • Notice some ions do not participate in reaction • = spectator ions • cross out spectator ions to get net ionic equation
Double Replacement Reactionsoccur with 2 ionic compound solutions • Products can be: - liquid (H2O) • - gas • - solid
H+1(aq) + OH-1(aq) H2O(l) Reactions that form Water HBr(aq) + NaOH(aq) H2O(l) + NaBr(aq) H+1(aq) + Br-1(aq) + Na+1(aq) + OH-1(aq) H2O(l) + Na+1(aq) + Br-1(aq)
H2O(l) + CO2(g) Reactions that form Gases HCl(aq) + NaHCO3(aq) H2CO3(aq) + NaCl(aq)
H+1(aq) + HCO3-1(aq) H2O(l) + CO2(g) Reactions that form Gases HCl(aq) + NaHCO3(aq) H2O(l) + CO2(g) + NaCl(aq) H+1(aq) + Cl-1(aq) + Na+1(aq) + HCO3-1(aq) H2O(l) + CO2(g) + Na+1(aq) + Cl-1(aq)
Conservation of Charge total charge (reactant side) must equal total charge on product side • 2OH-1(aq) + Cu2+(aq) Cu(OH)2(s) • -1 x 2 + +2 = 0 • H+1(aq) + OH-1(aq) H2O(l) • H+1(aq) + HCO3-1(aq) H2O(l) + CO2(g)