Bellwork: Answer these in your notes. What is the [H + ] of a solution with a ph of 4.90? Name this acid: H 3 PO 4. Name this base: KOH

Transcription

1 Bellwork: Answer these in your notes. What is the [H + ] of a solution with a ph of 4.90? Name this acid: H 3 PO 4 Name this base: KOH

2 Stoichiometry The stoichiometry of an acid-base neutralization reaction is the same as that of any other reaction that occurs in solution (they are double displacement reactions, after all). For example, in the reaction of sodium hydroxide and hydrochloric acid, 1 mol of NaOH neutralizes 1 mol of HCl: NaOH (aq) + HCl (aq) NaCl (aq) + H 2 O (l)

3 A 25 ml solution of H 2 SO 4 is completely neutralized by 18 ml of 1.0 M NaOH. What is the concentration of the H 2 SO 4 solution?

4 A 25 ml solution of H 2 SO 4 is completely neutralized by 18 ml of 1.0 M NaOH. What is the concentration of the H 2 SO 4 solution?

5 Titration Titration is a method for determining the concentration of a solution by reacting a known volume of that solution with a solution of known concentration.

6 Titration Procedure 1) A measured volume of an acidic or basic solution of unknown concentration is must be measured. 2) The titrating solution of known concentration is called the standard solution, or titrant. 3) Measured volumes of the standard solution are added slowly and mixed into the solution in the beaker. This process continues until the reaction reaches the equivalence point, which is the point at which moles of H + ion from the acid equal moles of OH - ion from the base.

7 In the titration of a strong acid by a strong base, a steep rise in the ph of the acid solution indicates that all of the H + ions from the acid have been neutralized by the OH - ions of the base. The point at which the curve flexes is the equivalence point of the titration. Bromthymol blue is an indicator that changes color at this equivalence point. Notice that phenolphthalein and methyl red don t match the exact equivalence point, but the slope is so steep that it doesn t matter.

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9 Indicators and Titration End Point Many indicators used for titrations. Each has its own particular ph or ph ranges over which it changes color. The point at which the indicator used in a titration changes color is called the end point of the titration. It is important to choose an indicator for a titration that will change color at the equivalence point of the titration. Remember that the role of the indicator is to indicate to you, by means of a color change, that just enough of the titrating solution has been added to neutralize the unknown solution. Equivalence point End point! BUT for strong-strong titrations, the ph change is so steep and so large, that the are approximately equal.

10 What s the Point of a Titration Again? To find the unknown concentration of an acid or a base. So you perform the actual titration noting the volume you started with and how much volume of the titrant you added and then you can calculate the concentration.

11 One commercial method used to peel potatoes is to soak them in a solution of NaOH for a short time, remove them from the NaOH, and spray off the peel. The concentration of NaOH is normally in the range of 3 to 6 M, and is periodically analyzed. In one such analysis, 45.7 ml of 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?

12 One commercial method used to peel potatoes is to soak them in a solution of NaOH for a short time, remove them from the NaOH, and spray off the peel. The concentration of NaOH is normally in the range of 3 to 6 M, and is periodically analyzed. In one such analysis, 45.7 ml of 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?

13 What is the molarity of NaOH solution if 48.0 ml are needed to neutralize 35.0 ml of.144 M H 2 SO 4?

14 What is the molarity of NaOH solution if 48.0 ml are needed to neutralize 35.0 ml of.144 M H 2 SO 4?

15 In the following acid-base neutralization, 1.68 g of the solid acid phenol (HC 6 H 5 O; MW = g/mol) neutralized ml of aqueous NaOH solution. Calculate the molarity of the base solution. HC 6 H 5 O(aq) + NaOH(aq) ---> NaC 6 H 5 O(aq) + H 2 O(l)

16 In the following acid-base neutralization, 1.68 g of the solid acid phenol (HC 6 H 5 O; MW = g/mol) neutralized ml of aqueous NaOH solution. Calculate the molarity of the base solution. HC 6 H 5 O(aq) + NaOH(aq) ---> NaC 6 H 5 O(aq) + H 2 O(l)

17 Titration Simulation- second titration HClO 4 and Sr(OH) 2 Give Out Titration Labs