What is the Molarity of ethanol in a "92 proof" solution of ethanol in water?

Question

In the United States, alcohol is rated according to "proof" which is usually defined as twice the percent by volume of pure ethanol in solution, measured at 60*F. What is the molarity of ethanol in a "92 proof" solution of ethanol in water. The density of ethanol (C2H5OH, molar mass=46g/mole) is 0.80g/cm^3 at 60*F; the density of water (H2O, molar mass= 18g/mole) is 1.0 gm/cm^3 at 60*F(15.5*C) Please Explain

Answer 1

92 proof is 46% by volume. So let's assume you have 1,000 mL of mix. So you have 460 ml of ethanol and 540 ml of water.

calculate the mass of ethanol

(460)(0.80) = grams of ethanol

Convert to moles by dividing by 46 g /mol

SInce it is 1 liter, this is also the molarity

Answer 2

there are a couple of fallacies in your argument; 1: ethanol is NOT a green alternative fuel. that myth started many years ago when emission testing first started and people would mix ethanol, and methanol, with gasoline to reduce emissions output. the problem is that the sensors designed to read gasoline emissions cant read alcohol emissions because alcohol burns too cold to be read by the sensors, thus emission output is "reduced". 2: you CAN make your own alcohol for fuel. all you need do is file some paperwork with the BATF, and perhaps you local state office as well. be prepared to pay road taxes of the fuel you produce though to keep the state and federal governments happy. you may be limited in the amount of fuel you can make per week though. when you make your own fuel, it has to be at least 160 proof, but higher is better. also you need to make some modifications to your car to be able run alcohol, these include larger injectors, higher capacity fuel pump, and perhaps some reprogramming of you cars computer if you have efi. with a carb you need to use larger jets, as well as opening up a couple of passage ways in the carb to allow more fuel to pass. remember that oyu need to run twice as much alcohol as gasoline.