The breathalyzer test used to measure blood alcohol content (BAC) is based on the redox reaction between dichromate ions and ethanol (C₂H₅OH, an alcohol) in acidic medium. What is the purpose of the breathalyzer test?
1) To measure the concentration of dichromate ions
2) To measure the concentration of ethanol
3) To measure the concentration of alcohol in the blood
4) To measure the concentration of oxygen in the breath