1. Reactions in Aqueous Solution

2. Reactions in aqueous solution Many reactions, esp. many double replacement reactions, occur in water. What happens when substances dissolve in water? Depends on if they are ionic or covalent.

3. Dissolving Covalent substance – sugar or C 6 H 12 O 6 C 6 H 12 O 6 (s)  C 6 H 12 O 6 (aq) The sugar molecules are spread out among the water molecules.

4. Dissolving Ionic substance – table salt or NaCl NaCl(s)  Na + (aq) + Cl - (aq) CaCl 2 (s)  Ca 2+ (aq) + 2Cl - (aq) AlCl 3 (s)  Al 3+ (aq) + 3Cl - (aq) The ions are spread out among the water molecules.

5. Double Replacement Reactions Often occur when you mix 2 solutions of ionic compounds. –1 product may be water or –1 product may be a gas or –1 product may be a solid We say these reactions “go to completion.”

6. Reactions producing Solids Precipitation: the opposite of dissolving! What do you see in the following clips: S1043.mov S1045.mov S1046.mov S1050.mov S1057.mov S1058.mov and S1060.movS1058.movS1060.mov

7. Reactions producing Solids 2 NaOH(aq) + CuCl 2 (aq)  2 NaCl(aq) + Cu(OH) 2 (s) Complete Chemical Equation

8. Complete Ionic Equations 2Na + (aq) + 2OH - (aq) + Cu 2+ (aq) + 2Cl - (aq)  2Na + (aq) + 2Cl - (aq) + Cu(OH) 2 (s) Ionic substances that dissolve are written as ions in solution!

9. Net Ionic Equations 2Na + (aq) + 2OH - (aq) + Cu 2+ (aq) + 2Cl - (aq)  2Na + (aq) + 2Cl - (aq) + Cu(OH) 2 (s) Notice that some ions do not participate in the reaction. They are spectator ions. Cross out all the spectator ions & you get the net ionic equation. 2OH - (aq) + Cu 2+ (aq)  Cu(OH) 2 (s)

10. Reactions that form Water HBr(aq) + NaOH(aq)  H 2 O(l) + NaBr(aq) H + (aq) + Br - (aq) + Na + (aq) + OH - (aq)  H 2 O(l) + Na + (aq) + Br - (aq) H + (aq) + OH - (aq)  H 2 O(l)

11. Reactions that form Gases HCl(aq) + NaHCO 3 (aq)  H 2 CO 3 (aq) + NaCl(aq) H 2 CO 3 (aq)  H 2 O(l) + CO 2 (g) ______________________________________ HCl(aq) + NaHCO 3 (aq)  H 2 O(l) + CO 2 (g) + NaCl(aq)

12. Reactions that form Gases HCl(aq) + NaHCO 3 (aq)  H 2 O(l) + CO 2 (g) + NaCl(aq) H + (aq) + Cl - (aq) + Na + (aq) + HCO 3 - (aq)  H 2 O(l) + CO 2 (g) + Na + (aq) + Cl - (aq) H + (aq) + HCO 3 - (aq)  H 2 O(l) + CO 2 (g)

13. Conservation of Charge Total charge on reactant side must equal total charge on product side.