Formal Chem Lab #1 (Penny) - Copper Concentration in...

This preview shows page 1 - 3 out of 7 pages.

Copper Concentration in PenniesPaige FerlandCHM 144MDr. DanielsonTA: FanConnor English, Andrew Garcia11/14/13Methods:Solution PreparationStandard Solutions:A 5.00 g/L stock Cu2+ solution is provided and around 40mLof this solution needs to be collected in the beginning of the lab. Obtain 6 50mLvolumetric flasks in which to hold the dilutions of the stock solution. 0.00mL,2.00mL, 4.00mL, 6.00mL, 8.00mL, and 10mL of stock solution are pipetted into thesix flasks respectively (make sure they are labeled).While the flasks are under thefume hood, 3mL of concentrated ammonia (15 M) is added to each solution, the flask1
is then filled to the line with distilled water and the six standard solutions areprepared.The concentration of each of the flasks should be calculated and recordedand two cuvettes obtained for use during the spectrometric analysis.Penny Solutions:Each student should have their own penny and from that pennycreate their own solution. The penny is weighed and the mass recorded in thenotebook. The age of the penny should also be written down as this pertains to thehypothesis of the lab. In the fume hood, place the penny in a 150mL beaker and add25mL of 6 M HNO3(measure using a graduated cylinder). The reaction should goto completion, when there is no solid left in the beaker. The beaker should then coolfor around 10 minutes. While still in the fume hood, all the contents from the beakershould be quantitatively transferred using a funnel and distilled water to make surethere is no loss of sample. Use 5-10mL to rinse the beaker and empty into the flask,repeat this step two more times emptying into the flask before the next rinse. Withflask still in fume hood, add 14mL of concentrated ammonia to the flask using agraduated cylinder. A blue color should develop; swirl to dissolve any solid left over.Dilute flask with distilled water, stopper, and invert to mix thoroughly.Absorbance MeasurementBefore measuring the absorbance of the standard solutions or the penny solutions itis necessary to determine the wavelength of maximum absorbance from aMeasureNet photodiode array (PDA) spectrophotometer. By looking at the givenspectrum within the range of 350 to 850 nm (200-350nm is caused by theabsorbance of light from the plastic cuvette and therefore, is not taken into account)the maximum wavelength value can be determined as the highest peak. Since thestock solution and the dilutions are blue in color the peak wavelength shouldcorrespond to the red LED color, as both blue and green would be reflected.

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 7 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Summer
Professor
NoProfessor

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture