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The Breathalyzer Test is an important REDOX Reaction. -Identify the reaction (chemical...

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gillianpierre | (Level 1) eNoter

Posted July 1, 2013 at 10:46 PM via web

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The Breathalyzer Test is an important REDOX Reaction.

-Identify the reaction (chemical equation)

-State what substance is being oxidized and which is being reduced

-Write the equation representing oxidationand reduction

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ncchemist | eNotes Employee

Posted July 2, 2013 at 1:39 AM (Answer #1)

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The standard breath analyzer test used by law enforcement to measure the blood alcohol content actually measures the amount of ethanol vapor in an exhaled breath which can then be used to estimate the blood alcohol content.  The ethanol is oxidized to acetic acid using oxygen.  The complete chemical reaction is written below.

CH3CH2OH + O2 -->  CH3CO2H + H2O

This is a redox reaction where one of the carbons in ethanol (CH3CH2OH) is oxidized to produce acetic acid (CH3CO2H).  At the same time, the oxygen (O2) is being reduced to water.  The half reaction for the oxidation is:

CH3CH2OH + H2O --> CH3CO2H + 4H+ + 4e-

The half reaction for the reduction is:

O2 + 4H+ + 4e- --> 2H2O 

Both of the half reactions add up to the first equation above.

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