Explain how catalytic converters reduce NOx and CO emissions from automobiles, and identify a potential byproduct concern if they are not functioning properly.

Explain how catalytic converters reduce NOx and CO emissions from automobiles, and identify a potential byproduct concern if they are not functioning properly.

• A. They catalyze oxidation of CO to CO2 and reduction of NOx to N2; implemented with precious metal catalysts; improper operation can lead to higher emissions of unburned hydrocarbons.
• B. They convert all pollutants into water vapor and oxygen; no byproducts occur.
• C. They only affect emissions of sulfur compounds.
• D. They contribute to ozone formation by releasing extra NOx.

Answer: (A)

The main idea is that catalytic converters use special catalysts to transform harmful gases in auto exhaust into less harmful ones, primarily oxidizing carbon monoxide (CO) to carbon dioxide (CO2) and reducing nitrogen oxides (NOx) to nitrogen (N2), while also helping oxidize unburned hydrocarbons. This three-way catalyst relies on precious metals like platinum, palladium, and rhodium and works best when the engine maintains a near-stoichiometric air-fuel ratio, guided by sensors that keep the mixture balanced so the reactions can proceed efficiently. If the converter isn’t functioning properly, its catalytic reactions slow or stop, so more pollutants slip through—most notably higher emissions of unburned hydrocarbons, along with CO and NOx. A byproduct concern highlighted here is the rise in unburned hydrocarbons when the converter is not working, which contributes to smog and health risks. The other options don’t fit because catalytic converters do not simply turn all pollutants into water vapor and oxygen, they do not specialize only in sulfur compounds, and they do not promote ozone formation by releasing extra NOx.

The main idea is that catalytic converters use special catalysts to transform harmful gases in auto exhaust into less harmful ones, primarily oxidizing carbon monoxide (CO) to carbon dioxide (CO2) and reducing nitrogen oxides (NOx) to nitrogen (N2), while also helping oxidize unburned hydrocarbons. This three-way catalyst relies on precious metals like platinum, palladium, and rhodium and works best when the engine maintains a near-stoichiometric air-fuel ratio, guided by sensors that keep the mixture balanced so the reactions can proceed efficiently. If the converter isn’t functioning properly, its catalytic reactions slow or stop, so more pollutants slip through—most notably higher emissions of unburned hydrocarbons, along with CO and NOx. A byproduct concern highlighted here is the rise in unburned hydrocarbons when the converter is not working, which contributes to smog and health risks. The other options don’t fit because catalytic converters do not simply turn all pollutants into water vapor and oxygen, they do not specialize only in sulfur compounds, and they do not promote ozone formation by releasing extra NOx.