CAIE A-Level Chemistry 12.1.4 NOx and Photochemical Smog

Practise explaining how NO and NO2 react with unburned hydrocarbons to form PAN in photochemical smog.

Exam points

identify NOx and unburned hydrocarbons as the pollutant pair involved in PAN formation
state that these engine-emission pollutants react in sunlight to produce peroxyacetyl nitrate
identify PAN as a component of photochemical smog rather than treating PAN and smog as synonyms

[Maximum number: 1]

Nitrogen and phosphorus are elements in Group 15 of the Periodic Table.

Nitrogen is found in inorganic compounds such as nitrogen oxides ( $\mathrm{NO}_{x}$ ), nitrates and nitric acid.

Peroxyacetyl nitrate, PAN, is a component of photochemical smog.

Describe how PAN forms from $\mathrm{NO}_{2}$ .

3 Nitrogen and phosphorus are elements in Group 15 of the Periodic Table.
(v) Describe what is seen when solid calcium nitrate is heated strongly.
(b) A common test for nitrates is the reaction with NaOH and Al . Equation 1 shows the reaction.

It / $\ce{NO2}$ reacts with (unburned) hydrocarbons / $\ce{VOCs}$

ALLOW reaction of unburned hydrocarbons / $\ce{VOCs}$ in presence of $\ce{NO2}$

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12.1.4—Atmospheric NOx and photochemical smog question 1