Question

Which of the following is not a common component of photochemical smog? (a) Peroxyacetyl nitrate (b) Acrolein (c) Formaldehyde (d) Carbon dioxide

Short answer

Carbon dioxide (d) is not a common component of photochemical smog.

Step-by-step solution

Understanding the Concept of Photochemical Smog

Photochemical smog is a type of air pollution that is created when sunlight reacts with nitrogen oxides and at least one volatile organic compound (VOC) in the Earth's atmosphere. It often results in a brownish-orange haze, particularly over cities during the warm, sunny periods of the year.

Identifying Common Components of Photochemical Smog

Common components of photochemical smog include ozone (O3), peroxyacyl nitrates (such as peroxyacetyl nitrate), aldehydes (such as formaldehyde and acrolein), and other secondary pollutants that form through reactions in the atmosphere.

Determining the Uncommon Component

By comparing the options given to the known components of photochemical smog, we can identify which one is not commonly found. Options (a), (b), and (c) are known components of photochemical smog, while (d) carbon dioxide, although a greenhouse gas, is not a direct product of the photochemical reactions that create smog.

Key concepts

Environmental Chemistry

Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. It involves examining the effects of chemicals and their reactions in the earth's environment, including the air, water, and soil. One significant aspect of environmental chemistry is the analysis of atmospheric chemistry and the understanding of pollutants that contribute to environmental degradation, such as those involved in the formation of photochemical smog.

At the core of environmental chemistry is the balance between natural processes and human activity. This includes the study of how human-generated substances interact with the natural environment and the potential consequences of these interactions. For instance, the emissions from vehicles and industrial processes release various compounds that can be harmful to our ecosystem. Scientists within the field of environmental chemistry strive to understand these processes, develop measures to control pollution, and find solutions to environmental problems like acid rain, ozone depletion, and photochemical smog.

Atmospheric Pollution

Atmospheric pollution refers to the presence of substances in the atmosphere that are harmful to living organisms or the environment. This type of pollution can result from both human activities and natural phenomena. The main culprits of human-induced atmospheric pollution are emissions from industries, transportation, and the burning of fossil fuels. These activities release a myriad of pollutants including nitrogen oxides, sulfur dioxide, volatile organic compounds (VOCs), and particulate matter into the atmosphere.

Atmospheric pollution has a variety of environmental and health impacts. For humans, it can cause respiratory issues, heart disease, and even affect cognitive function. On an environmental level, atmospheric pollutants can lead to issues like the greenhouse effect and global warming. Moreover, pollutants in the atmosphere can react with each other under certain conditions, such as in the presence of sunlight, leading to the creation of secondary pollutants and the complex mixture of photochemical smog, which significantly impacts air quality especially in urban areas.

Secondary Pollutants

Secondary pollutants are not emitted directly into the air; they form when primary pollutants react in the atmosphere. One example of secondary pollutants is ground-level ozone, which forms when nitrogen oxides (NOx) react with volatile organic compounds (VOCs) in the presence of sunlight. These reactions depend on various factors such as sunlight intensity, temperature, and the presence of other chemicals in the environment.

Among the secondary pollutants related to photochemical smog are peroxyacetyl nitrates (PANs), ozone (O3), and various aldehydes like formaldehyde and acrolein. These substances can have harmful effects on human health, vegetation, and materials. Efforts to reduce secondary pollutants typically focus on controlling the emissions of primary pollutants, which requires collective efforts and stringent regulatory measures. Understanding the formation and impact of these pollutants is crucial for developing effective strategies to improve air quality and protect public health.