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Lab 5 Inroduction to Spectroscopy

Lab 5 Inroduction to Spectroscopy - EXPERIMENT 5...

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Unformatted text preview: EXPERIMENT 5 INTRODUCTION TO SPECTROSCOPY Section 906 PRE-LABORATORY QUESTIONS 1. a. Define, spectroscopy. Méymdm amBSSisM 3 . The following preparatory questions should be answered before coming to lab. They are intended to introduce you to several ideas that are important to aspects of the experiment. You must turn in your work to your instructor before you will be allowed to begin the experiment. all: qclmae. deaf? at" SMWW’? ef- 012$}?- MO/mlo; ) am; ) 7m; 1 0;" Muriel, b. When you compare micro wave with infrared radiation, which one is more energetic? c. What type of radiation will be used in this experiment? V111 (to 1131/11 2. a. Define percent transmittance and absorbance. 710, imi'w‘fc-l'ifi 91’ #18 631““ 155ml» [flagggc 7122111314 fie. gamwle W161 W3 fire, defeelwr b. Write the mathematical relationship between the two. wg/ Cheml 5 ISfiAcademic Year 2010/201 1 / ‘r /0 1.111% M fiéiéfflfflm Mt Mo‘ué‘w (3‘12 3. What is 7» max? ”at Wavdmik 59* “We. {ii/imam am AéGEVéQMCQ 4. What is the purpose of the blank solution? 7; can ma 7%, Wmm M f, +0 find“ W its ccwi‘mj 49W 7% $6M rm, 5. a. State Beer’s Law mathematically and define each term. 719 A : ox 7< (X C 7% A“ r’iésssféma or? @(wtzm Q' aésawflwli—fi (/Acw we,“ W gubgéauu qéfefég £9290 fi'fa‘ifi faith (lug-15x £23142 fifimfeié hef‘ater} C: " Cm.c.w+ms§»tw $24 golweér‘é ma b. What important information about an analyte in solution can be determined from the spectrum? :1} «gm 11"st {55% g; éSw 6am) szw CGW‘ #«A 4119/ gmsflgméy—aézim’k Chem] 5 lS—«Aeademic Year 2010/201 l 5__2 Section 005 RESULTS PART ONE Table IV. Color of agent RED )‘vmax 500 Wavelength 400 420 Table V. Color of agent BLUE Xmax 5Z0 ,,,,,,____”Wayglsflgthn,,,,,_____j_,_,,,,,,,,,,4!z§qréq&9§ _____________ 500 ”,fi“.__fix,,,,_,,,,_V_____,___,d,,,,,,fi,,,,,J_____»_.,, ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, Cheml 5 lS—Academic Year 20 1 0/201 1 5‘_1 3 Wavelength (nm) Chem1515——Academic Year 2010/2011 5—1 4 Section 006 PART T W0 : Table VI. Absorbance readings for assigned Coloring Agent Color of food coloring agent (for the “—UNKNOWN”): 9 i ”L "—Test tube # labsorbance —'[ Relative Concentration l l 1 (WQW C 0% L 2 , 2’7 20L 1 2‘0 LID fifg , u? :30 V3 . 46": ‘59 9/0 _[ Man 100 % l | Sample Calculation for the Relative Concentration of Test Tube #2 £74} X/00% = 20% \ ”ma ,sqo:(m(7a.q) Fl Slope of the calibration line (plot on page 5-16) 090‘qu {\fy/W ‘ {\K C , 0051‘} ! y-intercept O \m. equation of the line (Z4 3 . 90 79 77/ ‘Unknown’ Absorbance Relative Concentration 7 number From computer plot From Beer’s plot (graph) (step 20 of Part Two — Page 5-16 page 5-12) ”fit: .er 1 WM m SIGN-OUT: All equipment is put away, and the student bench is clean and dry. ”\o TA Date Chem15 1 5*Academic Year 201 0/201 1 5—1 5 “do 0 O Absorbance J00 Chem15 15—Academic Year 2010/201 1 5—16 Nam” Section 0 0 6 W “— POST LABORATORY QUESTIONS 1. a. If a solution appears to be blue, What range of wavelength would you use for analysis of the solution? 49'0” “696 mm b. How about if the solution appeared to be yellow? 436’ #80 mm 2. a. What absorbance corresponds to a percent transmittance of 33.5 % T? fl; 2 , mg (“MB A: [I /0(7(3’7.6\) 2: ,406 b. What is the percent transmittance for a solution that has an absorbance of 0.15? A: Zr/OE! (901/) Chem15 15—Academic Year 2010/2011 5—1 7 a: Wfi 3. The concentration of metal ions can determined by: process known as ‘colorimetric ’ method in which the ion is combined with an organic material to form a colored solution. The colored solution was then subsequently analyzed by using a spectrometer. Mr. S. J. Taylor prepared a series of “metallic” ion standard solutions and measured their absorbance at 510 nm. His data is recorded as shown in the table below. Plot the data and determine the concentration of the “unknown”. Concentration, m a; E 35 '4: .3 <3: 4.0 5.0 an in . Concentration {mgih} Concentration of the unknown is (3: Z Mill. Cheml 5 lS—Academic Year 2010/201 1 5—1 8 , 4. At a wavelength of 274 nm (UV range) a 10 mg/L solution of caffeine gave a value of '\ 27.1 %.T. If the percent transmittance of an “unknown” solution of caffeine was found to be 18.5 %, what is the Waffeine in the “unknown”? ( Assume Beer’s law is obeyed) : Ze/o, (%T) , A (flail Z’/y(2’z/%> ., “(“4 “50074) 4:, WWW —> .66'7 = aim> L a; 7 a: Z'DQX/O'7(_£:_> MAM-”“3 5/. Chem1515—-Academic Year 2010/2011 5—1 9 Cheml 5 15—Academic Year 2010/2011 5—20 u ‘02, ...
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