1. Chem 1106

2.  Law Enforcement Used to prosecute drunk drivers with BAC’s above legal limit of 0.08%  Alcohol problems world wide problem  40 % of accidents are Alcohol related  BAC=Blood Alcohol Content  The ratio of breath alcohol to blood alcohol is 2100 : 1 % BAC = g Ethanol x 2100mL Breath x 100% 52.5 mL Breath 1mL Blood

3. What Happens to Alcohol in the Body?  Absorbed  capillaries, tissues and organs  Not Metabolized  remains a separate component in blood flow  Blood flow to alveoli  in the lungs, Ethanol evaporates from the blood into the breath since it is volatile, and is released with CO2 upon exhaling 

4. Alcohol in the brain BBB  Can cross the BBB  Blood brain barrier: barrier that separates the circulating blood from the brain extracellular fluid (BECF)  Alters neuronal membranes, ion channels, enzymes, and receptors.

5.  Ethanol reduces Potassium Dichromate turns it into the chromium ion thus you can observe a decrease the yellow color 2 K 2 Cr 2 O 7 + 3 CH 3 CH 2 OH + 8 H 2 SO 4 2 Cr 2 (SO 4 ) 3 + 2 K 2 SO 4 + 3 CH 3 COOH + 11 H 2 O

6.  Use spectrometer in real world application  Today they use Infrared detectors  Older method is the color  Both still apply  Beer’s-lambert Law A =  bc  %ethanol in an unknown sample

7.  Based on Beers Law  Concentration proportional to Absorbance  A=  bC

8. yellow range 383nm  Dichromate is colored yellow with absorbance in yellow range 383nm  Beer Law plot. So make it first  Then analyze an unknown sample of ethanol  Ethanol can only be given by TA  Use the stochiometery of the equation  Convert to % ALCOHOL (0.1% = 0.25 mg ethanol /mL )

9.  Dichromate is toxic and Corrosive  Green pad to protect the bench  Goggles, gloves and lab coats  Label as directed and prepare area, before coming for Dichromate solution

10.  Add 4 ml Sodium bisulfate solution and 20 ml water rinse the graduated cylinder with 5 mL water and add to beaker  Calibrate the spectrometer  Get dichromate, 10-15 ml for stock beaker  No solution will be issued If desk is not ready

11.  First need the stock solution concentration = pre-lab  Calculate the concentration using the linear regression curve y=mx+b 3. A= 442[Chromate] -0.00075

12. Step 1 [ chromate] from the stock solution to calculate how many moles of dichromate are available to react  (___mol Cr 2 O 7 -2 /L )* (0.005L )= ___mol Cr 2 O 7 -2 Step 2  Then use the[ Cr 2 O 7 -2] and the volume of the unknown solution ( mL) to calculate the # of moles of the dichromate ion in the unknown. (__mol Cr 2 O 7 -2 /L) *( __L) = __mol Cr 2 O 7 -2 How many moles of dichromate reacted with the ethanol?

13.  Answer 5a- answer 5b= mol Cr 2 O 7 -2 reacted w/ the ethanol  Moles Cr 2 O 7 -2 reacted w/ ethanol = _______mol Cr 2 O 7 -2  Next is about the stochimetery  2 moles of dichromate will consume 3 moles of ethanol.  Convert to the %BAC  0.10 %BAC = 0.025 mg ethanol/ mL of any  Correct the manual NOT /mL it is g/mol  [Answer from 7b]* [______ C 2 H 5 OH g/mole]* [___mg/g] = ____mg C 2 H 5 OH  % ERROR  known value –experimental known value calculate how many moles of dichromate there were before and after the reaction with ethanol? 2 K 2 Cr 2 O 7 + 8 H 2 SO 4 + 3 C 2 H 5 OH  2 Cr 2 (SO 4 ) 3 +2K 2 SO 4 + 3 CH 3 COOH +11 H 2 O

14.  Dilutions must be accurate (M1V1=M2V2)  Take your time here otherwise you are Doomed  Timing is critical for Experiment 2 min. and swirl solution  Take only the solution you need because waste is toxic  Clean station and turn off microlab

15. waste stock dilution

16. 1 Microlab  beer’s law [Stock sol’n]  molar concentration from prelab dilutions concentration (M1V1 = M2V2) 2, 3 and 4  equipment ready waste 10 mL NaHSO 4 1 mL Calibrate (water blank) K 2 Cr 2 O 7 ~12mL stock 7 5 6 8 Read abs 9 stock 10

17. 11 Rinse waste dilution 1 mL H 2 O 12 stock 5 mL K 2 Cr 2 O 7 13 14-16 dilution Read abs dilution 17 1 st Dilution M 1 V 1 = M 2 V 2 M stock V stock = M dil V dil M stock (5mL) = M dil (6mL) Prelab ?

18. dilut 1 17 2 nd Dilution M 1 V 1 = M 2 V 2 M stock V stock = M dil V dil M stock (5mL) = M dil (7mL) dilution 1 mL H 2 O 18 dilution 2 Read abs 19-20 dilut 2 21 21-26 READ Unknown procedure 1-3 dilution 1 mL UNKNOWN 6-7 stock 5 mL K 2 Cr 2 O 7 4-5 Unknown dilution Read abs 8-11