152 Exp 2 Report - Section: AD Lab Partner: Erika EXP 2:...

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Page 1 Section: AD Lab Partner: Erika Total Points = 60 pts PURPOSE AND METHOD DATA, CALCULATIONS AND GRAPHS A: Standardization of NaOH using KHP Table 1: Data for Calculation of [NaOH] Run #1, 1 pt Run #2, 1 pt Run #3, 1 pt** Mass of KHP 0.413 g Mass of KHP 0.401 g Mass of KHP n/a g Molar Mass, KHP 204.22 g/mole Molar Mass, KHP 204.22 g/mole Molar Mass, KHP n/a g/mole Initial buret reading 0.38 mL Initial buret reading 21.65 mL Initial buret reading n/a mL Final buret reading 21.65 mL Final buret reading 42.25 mL Final buret reading n/a mL mL Titrated 21.27 mL mL Titrated 20.60 mL mL Titrated n/a mL L Titrated 0.02127 L L Titrated 0.02060 L L Titrated n/a L [NaOH] 0.0951 M [NaOH] 0.0953 M [NaOH] n/a M Average [NaOH] 0.0952 M EXP 2: ACID-BASE TITRATION HELP KHP is potassium hydrogen phthalate, see manual for structure and molar mass. Review stoichiometry of reaction in the lab manual. Decide how many significant figures you need in the [NaOH] and format the number accordingly [Format --> Cells --> number --> number (change to desired number of decimal places]. Average =average(range of cells), excel will ignore text. It is a good idea to have the following available (I) Lab lecture Notes (ii) Lab Manual (iii) Lab Notebook (iv) Textbook Tips or text are presented with a white background, required work has a dark background This section has been completed for you as an example. There is no need for you to redo this section. Do not copy this into your lab notebook for your required Purpose & Procedure section - use this as a guide of what to include and write something in your own words. The purpose of this lab is to determine the concentration and dissociation constant of an acetic acid (HOAc) solution. The acid solution will be titrated with ~0.10 M sodium hydroxide while a pH meter is used to monitor the change in pH after each addition of base. The resulting titration curve (plot of pH versus volume of NaOH added) will be used to determine the equivalence point of the titration. Using the data from the titration curve, a derivative plot will be generated, the maximum of which identifies the volume of base added to reach the equivalence point. The volume of base added at the equivalence point, together with the concentration of the base and the volume of acid titrated, will be used to calculate the molarity of the acid according to the following equations: HOAc + NaOH → OAc - + H 2 O + Na + M acid *V acid = M base *V base There are two parts to this lab: (A) Standardization of the NaOH(aq) using potassium hydrogen phthalate (KHP). A known mass of KHP is titrated with NaOH(aq) to a phenolphthalein indicator endpoint. From the moles of KHP and the known stoichiometry of the reaction (1:1), the concentration of NaOH is calculated. (B) Titration of acetic acid, (HOAc) with NaOH(aq). The pH of the HOAc is measured as a function of volume of NaOH added. A plot of pH versus volume of NaOH added and a plot of
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This note was uploaded on 04/07/2008 for the course CHEM 152 taught by Professor Chiu during the Winter '08 term at University of Washington.

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152 Exp 2 Report - Section: AD Lab Partner: Erika EXP 2:...

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