1. Salts and Electrolysis Lab

2. Ionic compounds Made of positive ions = cations (metal or polyatomic ion) -AND- negative ions = anions (nonmetal or polyatomic ion) Salts = ionic compounds Greater the electronegativity difference the more ionic –See table S for eletronegativities –Difference in electronegativities >1.7 = ionic

3. Hydrolysis = salts dissociate in water  cations and anions (aqueous solution) Ex: NaCl + H 2 O  Na + (aq) + Cl - (aq) Cations = Na + Anions = Cl - Note: what happens to the water – some salts react with water  solutions of acids, bases, ions and salts.

4. 1) What happens when you dissolve salts in water? They form ions in solution

5. Gypsum Springs, Axel Heiburg Glacial melt flows through Gypsum Hill  Gypsum Springs

6. CaSO 4 = gypsum 2)What ions form when gypsum salts dissolve in water? CaSO 4 (s) + H 2 O  ___ Be sure to write the proper oxidation # that goes with each Ca +2 (aq) = cations SO 4 -2 (aq) = anions

7. Aqueous solutions = Electrolytes Electrolytes = ionic solutions that conduct electricity Add salt to water  salt ions Salt ions increase conductivity of water How can we test this???

8. Construct a Voltaic Cell (testing electrolytes)

9. Pre-lab Questions Using Table J which metal is more active Mg or Cu? Mg Mg and Cu act as electrodes (places where electrons move to and from.) Metals like to lose electrons so electrons flow from more active metals to less active ones. Which way will electrons flow if we use Mg and Cu electrodes? From Mg to Cu Which one will act as the anode? Mg

10. Using table J MgFe ZnAg MnSn AlCu AnodeCathode

11. Part 2: Electrolysis Add electricity to water  water molecules split Overall reaction is: 2H 2 O(l)  2H 2 (g) + O 2 (g)

12. Laws of Thermodynamics (energy laws) 1 st law = energy cannot be created or destroyed (just transformed from one type to another) 2 nd law = at every energy transformation some energy is lost in the form of heat (less usable form of energy)

13. Set up your electrolysis apparatus

14. Follow lab procedures for comparing electrolytes