What device in the exhaust system reduces harmful emissions by reacting chemically with exhaust?

The device in the exhaust system that reduces harmful emissions by chemically reacting with exhaust gases is the catalytic converter. This component plays a crucial role in controlling pollution by facilitating chemical reactions that convert harmful substances such as carbon monoxide, hydrocarbons, and nitrogen oxides into less harmful emissions, such as carbon dioxide and nitrogen. The catalytic converter contains catalysts, typically made from precious metals, that enable these chemical reactions to occur efficiently at high temperatures.

In contrast, the exhaust manifold is primarily responsible for collecting exhaust gases from the engine and directing them into the exhaust system. The muffler is designed to reduce noise produced by the engine's exhaust gases, while the resonator works to fine-tune the sound of the exhaust but does not have a significant impact on emissions reduction. Understanding the distinct functions of these components highlights the catalytic converter’s vital role in reducing the environmental impact of vehicle emissions.