Alcohol-based fuels for automobiles lead to the production of formaldehyde (CH2O) in exhaust gases. Formaldehyde undergoes photodissociation, which contributes to photochemical smog:
CH2O + hv → CHO + H
The maximum wavelength of light that can cause this reaction is 335 nm.
(a) In what part of the electromagnetic spectrum is light with this wavelength found?
(b) What is the maximum strength of a bond, in kJ / mol, that can be broken by absorption of a photon of 335-nm light?
(c) Compare your answer from part (b) to the appropriate value from Table 8.4.What do you conclude about C - H bond energy in formaldehyde?
Pollutant Conentration (PPm)
Carbon monoxide ..... 10
Hydrocarbons ......... 3
Sulfur dioxide ......... 0.08
Nitrogen oxides ....... 0.05
Total oxidants ......... 0.02
(ozone and others)
(d) Write out the formaldehyde photodissociation reaction, showing Lewis-dot structures.