Question

how can I determine the Blood alcohol content with this information?

Course Contents Prelab Questions Determination of Percent Breath Alcohol Content t30p20a Notes Evaluate Timer Feedback The chemical method of analysis in determination of the blood alcohol content (%BAC ) is: K2Cr2o7+ H2SO4+CaHsOHCr(SO4)3+ K2S04 + CH3C0OH+ H20 What are the stoichiometric coefficients for the reaction above? (please enter the coefficients without spaces and with a coma between the numbers, e.g. 1,2,3,4) 2,8,3,2,2,3,11 You are correct. Previous Tries Your receipt no. is 157-4258 During a Breathalyzer Test it was determined that 1.70mg of KCry07 Mas consumed by the above reaction. Calculate the number of milligrams of ethanol in the test sample. 0.399 You are correct. Your receipt no. is 157-6909 Previous Tries Calculate the Blood Alcohol Content in this sample (%BAC). Tries 0/99 Submit Answer Send This discussion is closed. T 28 MacBook Pro

Answer 1

mass of K2Cr2O7 = 1.70 mg = 0.0017 g

moles of K2Cr2O7 = 0.0017 mg / (294.19 g/mol) = 5.78*10^-6 mol

From the balanced equation:

Potassium dichromate and ethanol(C2H5OH) are in a 2:3 mole ratio.

moles of ethanol = 5.78*10^-6 mol*(3/2) = 8.67*10^-6 moles of ethanol

mass of ethanol = 8.67*10^-6 mol*(46.07 g/mol)

                             = 0.000399 g ethanol

                             = 0.399 mg ethanol

Blood alcohol content is usually measured in units of grams of alcohol per 100 mL of blood, multiplied by 100%.

Blood alcohol content = (mass of alcohol/volume of sample)*100

                                        = (0.399/100)*100

                                        = 0.399%