1. Detection of Ethanol

2. Detection of Ethanol DUI Synergistic action with other drugs
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)

3. Oxidative method of ethanol determination involves color change
C2H5OH + K2Cr2O7 + H2SO4→ CH3COOH + Cr2(SO4)3 + H2O + K2SO4
orange
green
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.

4. 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

5. Task 1: Determination of Unknown Concentration of Ethanol in Blood

6. 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!