CHEM 150 HOMEWORK #6 Due: Tuesday, 7/22/08 1.A 0.1002 g sample containing only CCl4and CHCl3was dissolved in methanol and electrolyzed at the surface of a mercury electrode at –1.0 V, which required 50.20 s at a constant current of 0.200 A. The potential of the cathode was then adjusted and held constant at –1.80 V. Completion of the titration at this potential required 382.35 s at a constant current of 0.200 A. Calculate the respective percentages of CCl4and CHCl3in the mixture. The electrolysis reactions are given below. 2CCl4+ 2H++ 2e-+ 2Hg(l) →2CHCl3+ Hg2Cl2(s) [occurs at –1.0V] 2CHCl3+ 6H+ + 6e-+ 6Hg(l) →2CH4+ 3Hg2Cl2(s) [occurs at –1.80V] 2.Phenol (94.11 g/mol) undergoes a quantitative reaction with bromine. 3Br2+ 3H2O + phenol →phenol·Br3+ 3Br -+ 3H3O+The bromine needed to react with the phenol in a 50.0 mL sample of disinfectant was generated electrically. The complete reaction required 10.40 min at a constant current of 80.0 mA (F = 9.6485 x 104C/mol e-). How much phenol (in mg/ml) is in the disinfectant sample?
This is the end of the preview.
access the rest of the document.