1.) The next three questions are related to the analysis of mercury (200.59 g/mol) in the sample of mercuric ointment described here.
A 4.031 g sample of a mercuric ointment is digested in nitric acid. After dilution, the Hg2+is titrated with 32.50 mL of a 0.2253 M solution of NH4SCN. The titration involves the formation of a stable, neutral complex:
Hg2+(aq) + 2 SCN-(aq) = Hg(SCN)2(aq)
A.) How many mmoles of mercury are in the sample?
B.) How many mg's of mercury are in the sample?
C.) What is the percent mercury (w/w) in the ointment?
2.) An analyst is to determine the molarity of a NaOH solution. Three aliquots of standard KHP are weighed out: 0.3174 g, 0.4949 g, and 0.3869 g. These three aliquots were titrated using a NaOH solution and required 15.34 mL, 24.23 mL, and 18.59 mL, respectively. From these data calculate the average molarity of the NaOH solution.
3.) A second analyst was attempting to determine the percent KHP in an unknown sample, similar to that in the CEM 262 laboratory experiment 1. The analyst found the molarity of the standardized NaOH solution to be 0.0998 mol/L. Three aliquots of the unknown sample having weights of 0.8172 g, 0.9379 g, and 0.8740 g were titrated with the NaOH solution requiring 17.45 mL, 22.45 mL, and 23.67 mL, respectively. From these data, determine the average percent KHP in the unknown sample.
4.) Exactly 50.00 mL of an HCl solution required 21.56 mL of 0.07408 M Ba(OH)2 to reach the end point. Calculate the molarity of the HCl solution.