Double Replacement Reactions In detail

Ionic Compounds in Water Because the ions in ionic compounds are attracted (not connected) to each other ionic compounds can dissociate in water. We can write the dissociated ions like this: Na+ + Cl- + K+ + NO3-  If all of the ions in a double replacement reaction STAYED aqueous, how would the products look?

Molecular, Ionic and Net Ionic Equations Molecular, Ionic and Net Ionic Equations So, in order for a change to occur, a product must become a solid, liquid, or gas. Sodium chloride and silver nitrate → sodium nitrate and silver chloride NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s) The AgCl is labeled with (s) because it is insoluble and forms a precipitate.

Molecular equations NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s) A molecular equation shows us all of the chemicals in a reaction, but doesn’t show how they are actually arranged.

Ionic Equation Na+ + Cl- + Ag+ + NO3- → Na+ + NO3- + AgCl(s) All substance are dissociated except for the insoluble AgCl(s) --This shows how the ions are arranged in the aqueous solution

Net Ionic Equation The ions not involved in forming the precipitate (Na+ and NO3-) are called "Spectator Ions" and are eliminated to form the net ionic equation. Ag+ + Cl- → AgCl(s)

How do you know what elements make the precipitate? --Use the Solubility Rules Soluble = stay aqueous Insoluble = become solid  Rule 1. Most nitrate salts are soluble. Rule 2. Most salts containing alkali metal ions and the ammonium ion are soluble.

Rule 3. Most chloride, bromide, and iodide salts are soluble Rule 3. Most chloride, bromide, and iodide salts are soluble. Exceptions are salts containing Ag, Pb, and Hg Rule 4. Most sulfate salts are soluble. Exceptions are salts containing Ba, Pb, Hg, and Ca Rule 5. Hydroxides are generally insoluble. Exceptions include salts containing cations in Rule 2 & Ca, Ba, and Sr. Rule 6. Most sulfide, carbonate, chromate and phosphates are insoluble, except for those with cations from rule 2.

Copper(II) chloride + sodium sulfide → copper(II)sulfide and sodium chloride ♦ Molecular: CuCl2 + Na2S → CuS + NaCl CuCl2 + Na2S → CuS(s) + 2NaCl ♦ Complete Ionic: Cu2+ + 2Cl- + 2Na+ + S2- → CuS(s) + 2Na+ + 2Cl- ♦ Net Ionic: Cu2+ + S2- → CuS(s) The spectator ions are Na+ and Cl-

Sodium bicarbonate plus hydrochloric acid yields sodium chloride plus water and carbon dioxide ♦ Molecular: NaHCO3(aq) + HCl(aq)  NaCl(aq) + H2O(l) + CO2(g) ♦ Complete Ionic: Na+ + HCO3 - + H+ + Cl -  Na + + Cl - + H2O(l) + CO2(g) ♦ Net Ionic: HCO3 - + H+  H2O(l) + CO2(g) Na+ and Cl- are spectator ions

3. Calcium chloride + sodium carbonate calcium carbonate and sodium chloride CaCl2 + Na2CO3 → CaCO3(s) + 2NaCl Ca2+ + 2Cl- + 2Na+ + CO32- → CaCO3(s) + 2Na+ + 2Cl- The spectator ions are Na+ and Cl- Ca2+ + CO32- → CaCO3(s)

3Ba(NO3)2 + 2Na3PO4 → Ba3(PO4)2(s) + 6NaNO3 4. Barium nitrate + sodium phosphate → barium phosphate and sodium nitrate Ba(NO3)2 + Na3PO4 → Ba3(PO4)2(s) + NaNO3 3Ba(NO3)2 + 2Na3PO4 → Ba3(PO4)2(s) + 6NaNO3 3Ba2+ + 6NO3- + 6Na+ + 2PO43- → Ba3(PO4)2(s) + 6Na+ + 6NO3- The spectator ions are Na+ and NO3- 3Ba2+ + 2PO43- → Ba3(PO4)2(s)

5. Chromium(III) chloride + silver nitrate → chromium(III) nitrate and silver chloride CrCl3 + 3AgNO3 → Cr(NO3)3 + 3AgCl(s) Cr3+ + 3Cl- + 3Ag+ + 3NO3- → Cr3+ + 3NO3- + 3AgCl(s) 3Ag+ + 3Cl- → 3AgCl(s) Ag+ + Cl- → AgCl(s)