"Did you drink? get a driver!"

Consumed alcohol enters the blood, partly in the lung and other organs, (including brains). It will affect the reaction power of the driver. In case of accidents, such a driver automatically is guilty. The police have different possibilities to check; one is based on a redoxreaction in the 'blow pipe'.

In that instrument is put potassium dichromate in acid environment with a yellow colour. If during the blowing, alcohol is oxydised by the yellow bichromate, a green substance (with Cr(III)-ions) is produced. If that is seen by the policeman, he wan't let you continue driving your car. The other product that is formed is acetic acid.