1. Welcome to station #8! To begin, advance to next slide… (by using space bar or key)

2. Question 1: advance to next slide for answer… During a titration, what is the purpose of an indicator? A. to keep the glassware clean B. to visualize the endpoint C. to prime the glassware D. so you can read the burets

3. During a titration, what is the purpose of an indicator? A. to keep the glassware clean B. to visualize the endpoint C. to prime the glassware D. so you can read the burets Question 1 answer: advance to next slide for next question… We used phenolphthalein to make the endpoint visible

4. Question 2: advance to next slide for answer… Which of these acids reacts with copper metal? A. HNO 3 (nitric acid) B. H 2 SO 4 (sulfuric acid) C. H 3 PO 4 (phosphoric acid) D. HCl (hydrochloric acid) E. H 2 CO 3 (carbonic acid)

5. Question 2 answer: advance to next slide for next question… Which of these acids reacts with copper metal? A. HNO 3 (nitric acid) B. H 2 SO 4 (sulfuric acid) C. H 3 PO 4 (phosphoric acid) D. HCl (hydrochloric acid) E. H 2 CO 3 (carbonic acid) found in battery acid found in colas stomach acid found in soda As a demo, we placed a quarter (which contains copper) in nitric acid in the fume hood.

6. Question 3: advance to next slide for answer… MgClO 4 is dissolved in water. The resulting solution will be… A. acidic B. basic C. neutral D. depends on k a /k b E. depends on molarity of resulting solution

7. Question 3 answer: advance to next slide for next question… - HClO 4 is a strong acid - Mg(OH) 2 is a weak base The resulting salt will be acidic! MgClO 4 is dissolved in water. The resulting solution will be… A. acidic B. basic C. neutral D. depends on k a /k b E. depends on molarity of resulting solution

8. Question 4: advance to next slide for answer… Consider a solution in which the [H + ] is greater than the [OH - ]. A. this solution could never exist B. this solution would be acidic C. this solution would be basic D. this solution would be neutral

9. Question 4 answer: advance to next slide for next question… Consider a solution in which the [H + ] is greater than the [OH - ]. A. this solution could never exist B. this solution would be acidic C. this solution would be basic D. this solution would be neutral Acidic solutions would contain more [H + ] than [OH - ], but their products are still 1 x 10 -14

10. Question 5: advance to next slide for answer… A buffered solution would contain H 3 PO 3 & what else? A. OH - B. H 2 PO 4 - C. H 3 O + D. HPO 4 -2 E. PO 3 -3

11. Question 5 answer: advance to next slide for next question… Buffered solutions always contain an acid with its conjugate base. A buffered solution would contain H 3 PO 3 & what else? A. OH - B. H 2 PO 3 - C. H 3 O + D. HPO 3 -2 E. PO 3 -3

12. Question 6: advance to next slide for answer… Is it possible to have a solution of HCl with a pH = 7?

13. Question 6 answer: advance to next slide for next question… Yes - if the solution is very dilute, then the [H + ] from the H 2 O dissociation (1 x 10 -7 M) would be greater than the [H + ] from the HCl dissociation. You saw this occur during the pH lab with the cabbage juice. Is it possible to have a solution of HCl with a pH = 7?

14. Question 7: advance to next slide for answer… In this reaction, HF + H 2 O H 3 O + + F - …what is the base? …what is the conjugate acid?

15. Question 7 answer: advance to next slide for next question… HF + H 2 O H 3 O + + F - H 2 O is accepting a H +, making it the base. Hydronium (H 3 O + ) is its conjugate acid. base conjugate acid acid conjugate base HF is donating the H +, making it the acid. F - is its conjugate base.

16. Question 8: advance to next slide for answer… Acetic acid (vinegar) is considered a weak acid because it is… A. insoluble in water B. dilute when in solution C. poorly dissociated D. not an Arrhenius acid

17. Question 8 answer: Acetic acid (vinegar) is considered a weak acid because it is… A. insoluble in water B. dilute when in solution C. poorly dissociated D. not an Arrhenius acid Weak acids are weak electrolytes. Acetic acid is only partially dissociated in water: HC 2 H 3 O 2 H + + C 2 H 3 O 2 - advance to next slide for next question…

18. Question 9: advance to next slide for answer… While cleaning dishes in the kitchen, someone adds drain cleaner (which contains lye) to red cabbage juice. What color will it turn? A. clear B. red C. colorless D. blue E. yellow F. blue G. purple H. pink

19. Question 9 answer: While cleaning dishes in the kitchen, someone adds drain cleaner (which contains lye) to red cabbage juice. What color will it turn? A. clear B. red C. colorless D. blue E. yellow F. blue G. purple H. pink That’s the end of station #8. Please advance to next slide to re-start for next group ! Lye is sodium hydroxide (NaOH), a strong base. Cabbage juice is yellow in basic solutions.