1. Do now: Yummy  Why do some recipes call for baking powder and others call for baking soda? (discuss with someone sits next to you)  Test 9/22  Take home quiz Thursday 9/18

2. Acid-Base Neutralization/Titration AP Chemistry

3. Acid/base rxn:  Acids: ionize in aqueous solution to form Hydrogen ions H +  Example of strong electrolyte: H 2 SO 4  Example of weak electrolyte: HSO 4 -1

4. Acid Base Neutralization Reaction AAcid + Base  Water + Salt EEx: HCl + NaOH  H 2 O + NaCl

5. Neutralization rxn and salts:  Litmus tests:  Blue to red is acid  Red to blue is base  Equation for litmus (red) turn blue  Le Chatelier's Principle

6. Example: Stomach antacids

7. Back to do now question:

8. Acid/base rxn with gas formation:  Other bases besides hydroxide react with acid  Such as sulfide ion and carbonate ion  Form gases  Carbonate and bicarbonates react with acids to form carbon dioxide

9. Monoprotic vs. diprotic:  HCl and HNO 3  H 2 SO 4

10. What is a Base?  Accept H + ions.  Produce hydroxide when dissolve in water  Look at the notecard for strong and weak acids/bases  Example: ammonia in water.

11. Concentration: Molarity (M) Moles of Solute Liters of Solution

12. Two ways to make a solution of know molarity : 1.just like what we did in lab, make our own solutions by using an accurately weighted amount of solute dissolved in solvent to an accurately calibrated volume. 2. Convenient way: - make up a solution quickly, using an estimated amount of solute and an estimated amount of solvent, then determine the solution’s exact molarity by titration

13. Titration:  Procedure for determining concentration [ ] of a solution by allow a carefully measured volume to react with a standard solution of another substance whose [ ] is known.  Find volume of standard solution that reacts with measured volume of 1 st solution, [ ] of 1 st solution can be calculated.

14. What does that mean?  Imagine we have HCl whose [ ] we want to find by allow to react with a base: NaOH (aq) + HCl (aq)  NaCl (aq) + H 2 O (l) 1.Begin titrate by: 1.Measure out a known volume of HCl 2.Add small amount of an indicator (phenolphthanlein) 1.Colorless in acidic but turns pink in basic 2.Fill calibrated glass tube/buret with NaOH of known [ ] 3.Slowly add NaOH to HCl until phenolphthalein turn pink 1.Indicate all HCl has reacted and solution is starting to become basic. 4.Read from buret to find volume of NaOH react with known volume HCl, calculate [ ] HCl

15. Buret Valve

16. Titration Acid with Phenolpthalein End-Point

17. Equivalence Point (talk about this later)  The point at which there are stoichiometrically equivalent amounts of acid and base.  [H+] = [OH-]

19. Indicators  Indicators are chosen, such that they change colors at the range of the pH of interest.  The solution itself at the end-point may be:  Basic, if the reaction involves a strong base and a weak acid.  Neutral, if the reaction involves a strong acid and a strong base.  Acidic, if the reaction involves a strong acid and a weak base.

20. Methods of Solving Titration Problems: a) using stoichiometry b) using the titration formula ( I don’t use this one often) aM a V a =bM b V b.

21. Ex: What is the concentration of HCl if 30.0 mL of 0.10 M NaOH neutralizes 50.0mL HCl? NaOH + HCl  H 2 O + NaCl

22. Ex: A 20.0 mL solution of Sr(OH) 2 is neutralized after 25.0 mL of standard 0.05 M HCl is added. What is the concentration of Sr(OH) 2 ? 2 HCl + Sr(OH) 2  2 H 2 O + SrCl 2

23. Ex:  How many mL of 0.20 M H 3 PO 4 are needed to neutralize 55.0 mL of a 0.10 M solution of NaOH?

24. Ex:  What volume of 0.20M Ca(OH) 2 will neutralize 45.0 mL of a 1M solution of HClO 3 ? 

25. Nikolas’ excellent question about acids strength:  Yesterday I said there is an Equation to calculate  Why H 2 SO 4 is stronger than HSO 4 -  How can we calculate acid strength?  Using pH  Deriving the Henderson-Hasselbach Equation  Are you ready???

26. Finally:  pH = pKa + log (base/acid)  pKa is from a table, already calculated for us.  Base and acid concentration you find out by doing lab  Question???

27. Do now:  Mr. Seidler came over this morning for some distilled water. He went into the chemical storage room and got a bottle but it wasn’t labeled. However, he was sure that the bottle is distilled water because Mrs. Cook always stored water in that container. How can we find out for sure?

28. 16) Calculate the molarity of the following solutions: a)23.4 g of sodium sulfate dissolved in enough water to form 125 mL of solution. b)5.00g of glucose (C 6 H 12 O 6 ) in sufficient water to form exactly 100 mL of solution.

29. 17) How many grams of Na 2 SO 4 are required to make 0.350 L of 0.500 M Na 2 SO 4 ? 18) What are the concentrations of each of the ions present in a 0.025 M aqueous solution of calcium nitrate?

30. 19) How many milliliters of 3.0 M sulfuric acid are needed to make 450 mL of 0.10 M sulfuric acid? (dilute) 20) How many grams of calcium hydroxide are needed to neutralize 25.0 mL of 0.100 M nitric acid?

31. 21) The quantity of chloride ion in a municipal water supply is determined by titrating the sample with silver ion as follows: Ag + (aq) + Cl - (aq)  AgCl(s) The end point of this titration is marked by a change in color of a special type of indicator.  How many grams of chloride ion are in a water sample if 20.2 mL of 0.100 M Ag + is used?  If the sample had a mass of 10.0 g, what is the percent of the chloride ion in the sample?

32. 22) A sample of an iron ore is dissolved in acid, and the iron is converted to Fe 2+. The sample is then titrated with 47.20 mL of 0.02240 M MnO 4 - solution resulting in the below oxidation-reduction reaction. MnO 4 - (aq) + 5 Fe 2+ (aq) + 8 H + (aq)  Mn 2+ (aq) + 5 Fe 3+ (aq) + 4 H 2 O (aq) a)How many grams of iron were in the sample? b)If the sample had a mass of 0.8890 g, what is the percent of the iron in the sample?

33. 23) One commercial method used to peel potatoes is to soak them in a solution of NaOH for a short time, remove and then spray off the peel. The concentration of NaOH is normally between 3 & 6 M. The NaOH is analyzed periodically. In one such analysis, 45.7 mL of 0.500 M H 2 SO 4 is required to neutralize a 20.0 mL sample of NaOH solution. What is the concentration of the NaOH solution?

34. 24)A sample of 70.5 mg of potassium phosphate is added to 15.0 mL of 0.050 M silver nitrate, resulting in the formation of a precipitate. a)Write the molecular equation for the reaction. b)What is the limiting reactant in the reaction? c)Calculate the theoretical yield, in grams, of the precipitate that forms.

35. Homework???