Breath analyzer

A final example of an application of balanced chemical equation involves the use of one form of the breath analyzer used by police to determine if someone was driving under the influence of alcohol. The chemical equation guiding the reaction when someone breaths into the instrument is... 

The equation shows that alcohol in the form of ethanol reacts with an orange solution of potassium dichromate to produce a green solution of chromic sulfate. The source of alcohol is the suspect s breath. More alcohol produces a greater color change. The breath analyzer measures this color change and coverts this measurement into an amount of alcohol in the blood. 

Several commercial evidential breath alcohol measurement devices are available. The principle of measurement is either infrared absorption spectrometry (most common), dichromate-sulfuric acid oxidation-reduction (photometric), GC (flame ionization or thermal conductivity detection), electrochemical oxidation (fuel cell), or metal-oxide semiconductor sensors. A list has been published of DOT-approved breath alcohol devices.Some of these devices are approved for screening only. In this case, the second or confirmatory breath alcohol determination must be performed with an approved evidential breath alcohol analyzer. Breath alcohol devices may also be used for the medical evaluation of patients at the point of care (e.g., emergency department). A Fourier transform infrared point-of-care breath analyzer capable of measurement of... 

Alcohol determinations at the roadside or at home are typically done with a breath analyzer or breathalyzer. Because of rapid gas exchange and the vapor pressure of ethanol, the concentration exhaled is directly related to the blood alcohol concentration. The blood alcohol concentration is widely used as a criterion for determining whether a person is under the influence of alcohol. Many states have ruled that a blood alcohol level of 0.1% or greater indicates intoxication. 

The alcohol in beverages, hair spray, and mouthwashes is ethanol. Ethanol is a volatile liquid that evaporates rapidly at room temperature. Because of this volatility, drinking an alcoholic beverage results in a level of gaseous ethanol in the breath that is proportional to the level of alcohol in the bloodstream. About 50 percent of all automobile accidents that result in a fatality are caused by intoxicated drivers. Law officers can determine quickly whether a person is legally intoxicated by using an instrument called a breath analyzer, or Breathalyzer. 

The police often use a device called a breath analyzer 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 breath analyzer, 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 ... 

Schematic diagram af a breath analyzer. The alcohol in the driver s breath is reacted with a potassium dichromate solution. The change in the absorption of light Meter registered by the de-...

Figure 2 A fuel cell-based evidential breath analyzer.

A New Blood Alcohol Breath Analyzer with Piezoelectric Detector. II. Effect of Composition on n-Octa-decanol Solvolysis of Zinc Stearate by Gas Chromatography Univ. Microfilms Int., Order No. 77-17,392, 221 pp. Diss. Abstr. Int. 38B(2) 629 (1977) CA 87 162299c... 

The Harger Drunkometer was the first breath analyzer, Introduced in 1938 to help convict drunk drivers. 

Don t Drink and Drive The Breath Analyzer Test (Ch. 8, Real Life 8-2, p. 294) Protecting-Group Strategy (Ch. 9, p. 350)... 

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