1. DDR

2. Double Displacement Reactions Will you find the PPT? I’ll give you six clues.

3. For the D.D. Reaction to happen one of the following must occur: A solid precipitate (PPT) must form Clue #1: We will only be looking for PPT formation in the DDR lab Liquid water must be produced in the reaction. A gas must form

4. Did you see it turn chalky white when I mixed AgNO 3 + BaCl 2 ????? What if it stays clear? Oh!! No Reaction!

5. Clue # 2: DDR has a pattern

6. I’d say we have a pretty “solid” relationship. Do I hear wedding bells?

7. “Double Displacement” means two ions change places. Na 2 CO 3 + BaCl 2 2 NaCl + BaCO 3 Reactants Products More on this in a minute…

8. Why did the ions switch places? They find another ion they are more strongly attracted to compared to a water molecule.

9. Water can dissolve soluble ionic solids like NaNO 3. Polarity allows water to slide between ions of opposite charge.

10. O The hydrogen side of H 2 O is positive and the oxygen side is negative.

11. Insoluble solids or “precipitates” prefer to stay in solid clumps rather than let a “.” slip between the ions.

12. Na+ NO 3 - Light passes through “clear” solutions Na+ Light reflects off insoluble cloudy “solids” or PPT’s Imagine there are water molecules between the ions.

13. “Double Displacement” means two ions change places. Na 2 CO 3 + BaCl 2 2 NaCl + BaCO 3 Reactants Products

14. Clue # 3: Only one of the products is the PPT Na 2 CO 3 + BaCl 2 2 NaCl + BaCO 3 Reactants Products NaCl ? or BaCO 3 ?

15. If NaCl is soluble, it cannot be a PPT Na 2 CO 3 + BaCl 2 2 NaCl + BaCO 3 Reactants Products How do you know if NaCl is soluble?

16. Clue # 4: If NaCl is one of the reagent bottles in the lab…and the solution in the bottle is clear…it is enough evidence to suggest it is always soluble. Solid NaCl crystals will dissolve into ions in water to make NaCl (aq).

17. What does (aq) mean? Why is (aq) superscripted after the formula NaCl (aq) ?

18. NaCl (aq). “(aq)” means Na+ and Cl- ions are present in aqueous solution. “Aqueous” means ions are dissolved in between water molecules.

19. Clue #5: If you can prove one of the products is soluble, or one of the reagent solutions, then it is logical the other product is GUILTY of being the insoluble PPT! Hint: Precipitates often “fall out” of solutions; so if you let it settle awhile the PPT may be easier to detect.

20. Clue #6 : If there is no reaction… at least make note of the aqeuous or soluble products. (Switch the negative ions for any combination to find new formulas of soluble solutions) BaCl 2 + 2NaNO 3 Ba(NO 3 ) 2 +2NaCl

21. Add the formula(s) to the list of products with an “alibi.” Guilty verdicts need only be “circumstantial” to complete this lab.

22. Solutions with an “alibi” PinkYellowGreyBlue-green NaNO 3 KNO 3 Co(NO 3 ) 2 K 2 CrO 4 NaBrKClFeCl 3 K 2 SO 4 Na 2 CO 3 NaClKOH Na 2 SO 4 CoCl 2 BaCl 2 NaOH AgNO 3 Add more to the list if the “products” of a combination = NR