Ionic Equations The order is: Top = molecular; middle = total ionic; bottom = net ionic. If phase is not shown that is because it is “aqueous” or water. 1. SnCl4 + 2 Pb(NO3)2 → 2 PbCl2(s) + Sn(NO3)4 Sn4+ + 4 Cl‐ + 2 Pb2+ + 4 NO3‐ → 2 PbCl2(s) + Sn4+ + 4 NO3‐ 4 Cl‐ + 2 Pb2+ → 2 PbCl2(s) Better: 2 Cl‐ + Pb2+ → PbCl2(s) Precipitation, with PbCl2 as the precipitate. 2. CuSO4 + Mg(s) → MgSO4 + Cu(s) Cu2+ + SO42‐ + Mg(s) → Mg2+ + SO42‐ + Cu(s) Cu2+ + Mg(s) → Mg2+ + Cu(s) Other type: You will learn on Monday that it is redox. The changing of the charges (e.g., magnesium metal—zero charge to magnesium ion‐‐+2 charge.) is your clue. Don’t add charges that are not there. It’s easy to do in this type of question! 3. 3 Ni(OH)2(s) + 2 H3PO4 → Ni3(PO4)2 (s) + 6 H2O 3 Ni(OH)2(s) + 2 H3PO4 → Ni3(PO4)2 (s) + 6 H2O 3 Ni(OH)2(s) + 2 H3PO4 → Ni3(PO4)2 (s) + 6 H2O Both precipitation (nickel(II) phosphate) and acid‐base. Yes, all three reactions are the same. Yes, phosphoric acid can be soluble without making ions, it is a covalent compound after all. 4. 3 KNO3 + FeBr3 → Fe(NO3)3 + 3 KBr 3 K+ + 3 NO3‐ + Fe3+ + 3 Br‐ → Fe3+ + 3 NO3‐ + 3 K+ + 3 Br‐ No net ionic reaction This is not a reaction, although it looked like it should be. Yes, you have to explicitly state there is no net ionic reaction. Beware: If this happens a lot you are probably doing it wrong. 5. 3 H2S + 2 CrI3 → 6 HI + Cr2S3(s) 3 H2S + 2 Cr3+ + 6 I‐ → 6 H+ + 6 I‐ + Cr2S3(s) 3 H2S + 2 Cr3+ → 6 H+ + Cr2S3(s) Precipitation reaction. Chromium(III) sulfide is the precipitate. 6. Ammonia and perchloric acid react to yield ammonium perchlorate. NH3 + HClO4 → NH4ClO4 NH3 + H+ + ClO4‐ → NH4+ + ClO4‐ NH3 + H+ → NH4+ Acid (HClO4) ‐ Base (NH3) reaction. It is a myth that all such reactions make water. 7. CoCl2 + 2 Na(s) → 2 NaCl + Co(s) 2+
‐
Co + 2 Cl + 2 Na(s) → 2 Na+ + 2 Cl‐ + Co(s) Co2+ + 2 Na(s) → 2 Na+ + Co(s) Other type of reaction. Another redox, did you see it? You cannot simplify the stoichiometric coefficients here. You can only do that if you divide EVERY coefficient by the same number. Simplifying would upset the charge balance. Do you notice than in addition to having the same number of each kind of atom, the total charge is the same on each side…always? 8. Ba(OH)2 + 2 NH4Cl → BaCl2 + 2 NH3 + 2 H2O Ba2+ + 2 OH‐ + 2 NH4+ + 2 Cl‐ → Ba2+ + 2 Cl‐ + 2 NH3 + 2 H2O 2 OH‐ + 2 NH4+ → + 2 NH3 + 2 H2O I would expect you to say “other” although under some definitions it could be classed as acid‐
base. 9. 2 CH3COOH + Na2CO3 → 2 NaCH3CO2 + H2O + CO2(g) 2 CH3COOH + 2 Na+ + CO32‐ → 2 Na+ + 2 CH3CO2‐ + H2O + CO2(g) 2 CH3COOH + CO32‐ → 2 CH3CO2‐ + H2O + CO2(g) Reaction type: acid‐base. Yes, I forgot to put carbonates and bicarbonates on your list of bases. Drat. Hopefully you saw it in your book. Acetic acid (CH3COOH) is soluble (like all common acids) but does not make ions. The solubility rules cannot be used for it BECAUSE IT IS NOT AN IONIC COMPOUND. You can use them for ionic sodium acetate however. You know carbon dioxide is a gas. 10. Li2SO4 + Ba(OH)2 → 2 LiOH + BaSO4(s) 2 Li+ + SO42‐ + Ba2+ + 2 OH‐ → 2 Li+ + 2 OH‐ + BaSO4(s) SO42‐ + Ba2+ → BaSO4(s) Precipitation! 11. aluminum iodide and mercury(I) nitrate react to make aluminum nitrate and mercury(I) iodide 2 AlI3 + 3 Hg2(NO3)2 → 2 Al(NO3)3 + 3 Hg2I2(s) 2 Al3+ + 6 I‐ + 3 Hg22+ + 6 NO3‐ → 2 Al3+ + 6 NO3‐ + 3 Hg2I2(s) 6 I‐ + 3 Hg22+ → 3 Hg2I2(s) memorize! Precipitation. Yes, mercury(I) is that wacko ion. Still, it’s on your list of polyatomics to 12. sulfuric acid and zinc metal react to make hydrogen gas and zinc sulfate H2SO4 + Zn(s) → H2(g) + ZnSO4 2 H+ + SO42‐ + Zn(s) → H2(g) + Zn2+ + SO42‐ 2 H+ + Zn(s) → H2(g) + Zn2+ “other”, another “redox” in fact. 13. 14. 2 HClO4 + K2O → H2O + 2KClO4 2 H+ + 2 ClO4‐ + 2 K+ + O2‐ → H2O + 2 K+ + 2 ClO4‐ 2 H+ + O2‐ → H2O Acid‐base! 2 HF + FeS(s) → H2S + FeF2 2 HF + FeS(s) → H2S + Fe2+ + 2 F‐ 2 HF + FeS(s) → H2S + Fe2+ + 2 F‐ Other! For once, not redox. Some texts call it “gas forming” as hydrosulfuric acid is not entirely dissolved in solution, something your nose would confirm as it produces the “rotton egg” smell. 15. TiCl4 + 2 Li2O → TiO2(s) + 4 LiCl Ti4+ + 4 Cl‐ + 4 Li+ + 2 O2‐ → TiO2(s) + 4 Li+ + 4 Cl‐ Ti4+ + 2 O2‐ → TiO2(s) Precipitation.