Chem+102+Quiz+3b+2010+-+answer+key

Chem+102+Quiz+3b+2010+-+answer+key - 3 organic solvents...

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Quiz #3 Name b Lab Section: Answer all calculation questions to the correct number of significant figures. 1. Using the data provided below. Create a standard curve and determine the concentration of the diluted unknown (500 ! L of the unknown ‘stock unknown’ was diluted to 10 mL.) and the ‘stock unknown’.(10 pts) Standard Data [MnO 4 - ] (mM) 0.00 2.50 5.00 7.50 10.00 Abs 0.002 0.075 0.165 0.220 .305 Unknown Data Diluted Unknown Abs (0.500 mL) 0.175 Unknown Stock Concentration 11.4 mM Absorbance (A.U.) Concentration (mM) 0.00 2.50 5.00 7.50 10.00 1.00 2.00 3.00 + + + + + 0.572 mM M 1 V 1 =M 2 V 2 M 1 =M 2 V 2/ V 1 M 1 =0.572mM ! 10.00mL / 0.500mL M 1 =11.4 mM
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Answer all calculation questions to the correct number of significant figures. 2. In this lab, what will be the stationary phase and the moving phase? (2 pts) The stationary phase will be the silica gel on the chromatography plate. The moving phase will be the organic developing solution made of a mixture of
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Unformatted text preview: 3 organic solvents (ethyl acetate, hexane and methanol) mixed with some diluted ammonium hydroxide. 3. In the following TLC plate, a sample of a medication (Med) was run against a standard (Std). Determine the solvent distance and the R f value for each component. (4 pts) Standard = 3.65 cm Rf = 3.65 cm / 5.12 cm = 0.713 Unknown 2 =3.72 cm Rf= 3.72 cm / 5.12 cm = 0.726 Unknown 1 =2.38 cm Rf= 2.38 cm / 5.12 cm = 0.465 Solvent front = 5.12 cm 4. How many components are in the medication above? (1 pts) 2 5. Does the medication contain the standard? Justify your answer. (3 pts) Yes, the medication probably contains the standard. Unknown 2 has an Rf value very close to the Rf value of the Standard. To be more conclusive, the visualization pattern of Unknown 2 should be compared with the Standard. Std Med Solvent Front Note Rf values are unitless...
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Chem+102+Quiz+3b+2010+-+answer+key - 3 organic solvents...

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