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March 17, 2010. Get a h/w page, Organization tree w/s, and a solubility rules page Complete the Warm up at your table (Single replacement and combustion) You will need paper and something to write with Today we will be discussing: “How do you recognize and represent chemical changes?”.
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March 17, 2010 • Get a h/w page, Organization tree w/s, and a solubility rules page • Complete the Warm up at your table (Single replacement and combustion) • You will need paper and something to write with • Today we will be discussing: “How do you recognize and represent chemical changes?” Important Dates: 4/2: Reaction Test Homework: Double Replacement W/S
Double Replacement • Double Replacement Reactions: • A reaction which involves the exchange of ions between two compounds • AB + CD → AD + CB • Ca(OH)2(aq) + 2HCl(aq) → CaCl2(aq) + 2H2O(l) • 2NaOH(aq) + CuCl2(aq) → 2NaCl(aq) + Cu(OH)2(s)
Double Replacement Predicament • All in aqueous solutions! • 3 types of Double Replacement reactions • Formation of precipitate • Formation of water • Formation of a product which decomposes into a gas
Formation of Precipitate • Solubility rules!!!!! • AB(aq) + CD(aq) → AD(aq) + CB(s) • NaCl(aq) + AgNO3(aq) → AgCl(s) + NaNO3(aq) • BaCl2(aq) + Na2SO4(aq) → ? • BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq) • Na2SO4(aq) + CaCl2(aq) → ? • Na2SO4(aq) + CaCl2(aq) → CaSO4(s) + NaCl(aq)
Formation of Water • Between Acids and Bases (H+/OH-) • HX(aq) + YOH(aq) → XY(aq) + H2O(l) • HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) • H2SO4(aq) + Mg(OH)2 → ? • H2SO4(aq) + Mg(OH)2 → MgSO4(aq) + H2O(l) • H3PO4(aq) + KOH → ? • H3PO4(aq) + KOH → K3PO4 + H2O(l)
Formation of a product which decomposes into a Gas • Three products will decompose into gasses: • H2CO3 → CO2(g) + H2O(l) • NH4OH → NH3(g) + H2O(l) • H2SO3 → SO2(g) + H2O(l) • CaCO3(s) + HCl(aq) → H2CO3(aq) + CaCl2(aq) • NaOH(aq) + NH4Br(aq) → NaBr(aq) + NH4OH(aq) • H2CO3 → CO2(g) + H2O(l) • NH4OH → NH3(g) + H2O(l)
Miscellaneous • Some DR can create gases without decomposition of a product • Not very common, but they do occur • HCl(aq) + FeS(s) → FeCl2(aq) + H2S(g) • NaCN(aq) + HCl(aq)→ NaCl(aq) + HCN(g)
Double Replacement Reactions • AsCl3(aq) + H2S(aq) → ? • 2AsCl3(aq) + 3H2S(aq) → As2S3(s) + 6HCl(aq) • HCl(aq) + CaCO3(aq) → ? • 2HCl(aq) + CaCO3(aq) → CO2(g) + CaCl2(aq) + H2O(l) • FeCl3(aq) + NaOH(aq) → ? • FeCl3(aq) + 3NaOH(aq) → Fe(OH)3 + 3NaCl(aq) • H2SO4 + KOH → ? • H2SO4 + 2KOH → 2H2O(l) + K2SO4(aq) • HNO3 + Ca(CN)2 →? • 2HNO3+ Ca(CN)2→2HCN + Ca(NO3)2