Question

i need help with pre-lab questions

Pre-Lab Questions The titration curve below (on the next page) was obtained by titrating 25.00 mL of a boric acid solution with a 1.000 M NaOH solution. Use the information given on the titration curve to answer the following questions: 1. What is the formula and value of K, for boric acid? Calculate using the half equivalence data point, and using the pH at one-quarter and three-quarter points, too. What is the average Ka from these three data points? 2. Is boric acid a stronger or weaker acid than acetic acid? 3. What was the concentration of the original boric acid solution? Materials Titration of Boric Acid with NaOH 14 12 20.00 ml 10 9.13 10.00 ml pH = 4.17 0.00 10 15 20 25 Volume of NaOH added (mL) Procedure Part I. Preparing a solution of your unknown weak acid Obtain a vial containing an unknown weak acid, which will be a solid. Quantitatively transfer the suggested mass (on the unknown vial) of the unknown acid into a 250-m volumetric flask using a milligram balance. Rather than using a weigh boat, use the f determining the mass of the unknown acid. Fill the flask about half full with deionize water. Swirl until all the acid dissolves. (This may take a while.) Then add deionized just up to the 250.00-mL mark. Invert the flask several times for the final mixing Part II. Performing a trial titration using phenolphthalein indicator hout 100 mL of standardized NaOH solution in a clean dry flask or beaker. Ri fill tho huret to iust under the 0

Answer 1

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