During a Breathalyzer Test it was determined that 1.60mg of K2Cr2O7 was consumed by the above reaction. Calculate the number of milligrams of ethanol in the test sample.
2 answers
2K2Cr2O7 + 8H2SO4 + 3C2H5OH → 2Cr2(SO4)3 + 2K2SO4 + 3CH3COOH + 11H2O
Convert 1.60 mg K2Cr2O7 to mg C2H5OH as follows:
mols K2Cr2O7 = 0.00160/molar mass K2Cr2O7.
Using the coefficients in the balanced equation, convert mols K2Cr2O7 to mols C2H5OH. That's mols K2Cr2O7 from above x (3 mols C2H5OH/2 mols K2Cr2O7) = mols K2Cr2O7 from above x (3/2) = ?
Then grams C2H5OH = mols C2H5OH x molar mass C2H5OH and convert g to mg.
mols K2Cr2O7 = 0.00160/molar mass K2Cr2O7.
Using the coefficients in the balanced equation, convert mols K2Cr2O7 to mols C2H5OH. That's mols K2Cr2O7 from above x (3 mols C2H5OH/2 mols K2Cr2O7) = mols K2Cr2O7 from above x (3/2) = ?
Then grams C2H5OH = mols C2H5OH x molar mass C2H5OH and convert g to mg.