Question

The compound used in the breath analysis test for drunken driving is?

Answer 1

The compound used in breath analysis test for drunken driving:

• The breath analyzer mostly contains a chamber including several compounds i.e Potassium dichromate, Sulphuric acid, and Silver nitrate, to support these reactions.
• Potassium dichromate is known to be a red-orange colour compound, which in the presence of an acid, acts as an oxidizing agent and converts Ethanol to Ethanoic acid, which can be given by the reaction:
  $\underset{\left(\mathrm{Ethanol}\right)}{3\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{OH}\left(\mathrm{l}\right)}+\underset{\left(\mathrm{Potassium}\mathrm{dichromate}\right)}{2{\mathrm{K}}_2\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Sulphuric}\mathrm{acid}\right)}{8{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4\left(\mathrm{l}\right)}\to \underset{\left(\mathrm{Ethanoic}\mathrm{acid}\right)}{3\mathrm{C}{\mathrm{H}}_3\mathrm{COOH}\left(\mathrm{l}\right)}+\underset{\left(\mathrm{Chromium}\left(\mathrm{III}\right)\mathrm{sulfate}\right)}{2\mathrm{C}{\mathrm{r}}_2(\mathrm{SO}4{)}_3\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Potassium}\mathrm{sulfate}\right)}{2{\mathrm{K}}_2\mathrm{S}{\mathrm{O}}_4\left(\mathrm{aq}\right)}+\underset{\left(\mathrm{Water}\right)}{11{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$
• Here the Potassium dichromate acts as an oxidizing agent and is itself getting converted to Chromium(III) sulfate, which is green in colour.
• The major application of this reaction is used in a breath analyzer by traffic police in case of drunken driving.
• When a person consuming alcohol breathes into the analyzer, the Potassium dichromate and Sulphuric acid present in the analyzer make it come in contact with alcohol vapour.
• This brings about the redox reaction, Where Alcohol gets oxidized to Acetic acid, and the colour of chromium changes from orange to green, as it gets converted into Chromium(III) sulfate and this is directly related to alcohol consumed.

Hence, the compounds used in the breath analysis test for drunken driving are Potassium dichromate and Sulphuric acid.