AP Environmental Science Flashcards: Photochemical Smog
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Review key ideas with interactive flashcards. This set includes 11 cards to help you master important concepts.
Identify two examples of VOCs provided in the text.
The text provides formaldehyde and gasoline as examples of Volatile Organic Compounds (VOCs).
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Identify two examples of VOCs provided in the text.
The text provides formaldehyde and gasoline as examples of Volatile Organic Compounds (VOCs).
What is the primary strategy for reducing photochemical smog?
The main method is to reduce the emission of its precursors: nitrogen oxides (NOx) and volatile organic compounds (VOCs).
During which part of the day are nitrogen oxides typically produced at high levels?
Nitrogen oxide is produced early in the day, often corresponding with morning rush hour traffic.
What role do heat and sunlight play in the formation of photochemical smog?
Heat and sunlight act as catalysts, providing the necessary energy for the chemical reactions between nitrogen oxides and VOCs to occur and form smog.
What are the primary ingredients required for the formation of photochemical smog?
Photochemical smog requires nitrogen oxides (NOx), volatile organic hydrocarbons (VOCs), heat, and sunlight to form.
What are Volatile Organic Compounds (VOCs)?
VOCs are compounds, such as formaldehyde and gasoline, that evaporate or sublimate easily at room temperature.
What is photochemical smog?
It is a type of air pollution formed when nitrogen oxides and volatile organic hydrocarbons react with heat and sunlight to produce a variety of pollutants.
Why do ozone concentrations typically peak in the afternoon?
Ozone is produced by chemical reactions between oxygen and sunlight, and sunlight is most intense in the afternoon, leading to peak production.
Besides industrial sources, what is a major natural source of VOCs?
Trees are a significant natural source of Volatile Organic Compounds (VOCs).
A city notes high levels of nitrogen oxides during the morning commute and high levels of ozone in the late afternoon. What phenomenon is occurring?
This daily pattern indicates the formation of photochemical smog, where morning pollutants (NOx) react with sunlight throughout the day to form secondary pollutants like ozone.
Why is photochemical smog generally more prevalent in the summer?
Smog formation is worse in the summer because the creation of ozone, a key component, requires the intense heat and sunlight characteristic of that season.