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Detection of Ethanol. Detection of Ethanol. DUI Saliva (coupled enzyme assay) [“On-Site”] Breathylizer BAC via breath “Breathalyzer” (visible spec) “Intoxilyzer 5000” (infrared spec) “Alco-Sensor” (fuel cell) “Alcohawk” (solid-oxide conductor) Urine Blood (directly)
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Detection of Ethanol • DUI • Saliva (coupled enzyme assay) [“On-Site”] • Breathylizer • BAC via breath • “Breathalyzer” (visible spec) • “Intoxilyzer 5000” (infrared spec) • “Alco-Sensor” (fuel cell) • “Alcohawk” (solid-oxide conductor) • Urine • Blood (directly) • Chromic acid oxidative method • Synergistic action with other drugs • Poisoning (ethanol and methanol)
Oxidative method of ethanol determination involves color change C2H5OH + K2Cr2O7 + H2SO4→ CH3COOH + Cr2(SO4)3 + H2O + K2SO4 green orange Our Tasks: 1. Use the above reaction to help us determine an unknown ethanol concentration. 2. Use the above reaction to help us explore limiting reagents.
Determination of Unknown Concentration of Ethanol in Blood • Beer’s Law: A = bc • The absorbance of a solution is linearly proportional to it’s concentration. • We can make a calibration curve, do a linear fit, and solve for the unknown
Task 1: Determination of Unknown Concentration of Ethanol in Blood
Task 2: Investigate the stoichiometry of the reaction C2H5OH + K2Cr2O7 + H2SO4→ CH3COOH + Cr2(SO4)3 + H2O + K2SO4 Task 3: If 0.2 mL of an ethanol solution is mixed with 20.0 mL of a solution prepared by dissolving 50 mg of K2Cr2O7 in 100 mL of deionized water and diluting to 200 mL with concentrated sulfuric acid, what molarity must the ethanol be to completely consume all of the potassium dichromate? In order to answer the above question, we need to learn about balancing reactions and reaction stoichiometry!