# What is the precaution that you must take regarding

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1.What is the precaution that you must take regarding the use of the stirring bar? 2.What is the difference between a monoprotic and diprotic acid? How would their titration curves differ? 3.What is the difference between an equivalence point and an end point? 4.A 0.200 gram sample of a weak monoprotic acid required 29.41 mL of 0.100 M NaOH for neutralization. Calculate the molar mass of the acid. 5.At the beginning of the titration, how much titrant should be added between pH readings? As you approach the equivalence point how much acid should be added until you reach the equivalence point?
Determining the Kaof a Weak Acid POST-LAB (Note: ask instructor which numbers you are responsible for) 1.Plot the pH of the solution on the ordinate and the volume of standard base on the abscissa on linear graph paper. Refer to the section in the Introduction describing good graphing technique. 2.Calculate the number of moles of NaOH solution needed Lo reach the equivalence point. 3.Calculate the molar mass of the acid in both Part 1 and Part 2. 4.From your titration curve, determine the pKa and Ka of your unknown acid. Record their values on the report sheet. 5.Identify the unknown acid by comparing its experimental pKa and molar mass with those listed in Table I. Record your unknown acid on the report sheet.
6.How would the pKa of the unknown acid be affected (higher, lower, or no change) if the following errors occurred? Briefly explain why in each case. a.The pH meter was incorrectly calibrated to read lower than the actual pH. b.During the titration several drops of NaOH missed the reaction beaker and fell onto the bench top. c.In Part B of the procedure the acid was dissolved in 75 mL of distilled water rather than the 50 mL called for in the procedure. 7.How would the molar mass of the unknown acid be affected (higher, lower, or no change) if the follow-ing errors occurred? Briefly explain why in each case.