Answer:
c. alcohol oxidation
Step-by-step explanation:
The police often use a device called a breathalyzer to test drivers suspected of being drunk. The chemical basis of this device is a redox reaction. A sample of the driver’s breath is drawn into the breathalyzer, where it is treated with an acidic solution of potassium dichromate. The alcohol (ethanol) in the breath is converted to acetic acid as shown in the following equation:
3 CH₃CH₂OH + 2 K₂Cr₂O₇ + 8H₂SO₄ → 3 CH₃COOH + 2 Cr₂(SO₄)₃ + 2 K₂SO₄ +1 11H₂O
ethanol + potassium dichromate (orange yellow) + sulfuric acid → acetic acid + chromium(III) sulfate (green) + potassium sulfate + water
In this reaction, the ethanol is oxidized to acetic acid and the chromium(VI) in the orange-yellow dichromate ion is reduced to the green chromium(III) ion. The driver's blood alcohol level can be determined readily by measuring the degree of this color change (read from a calibrated meter on the instrument).