(a) If you were going to build a system to check the effectiveness of automobile catalytic converters on cars, what substances would you want to look for in the car exhaust? (b) Automobile catalytic converters have to work at high temperatures, as hot exhaust gases stream through them. In what ways could this be an advantage? In what ways a disadvantage? (c) Why is the rate of flow of exhaust gases over a catalytic converter important?

To evaluate the effectiveness of an automobile catalytic converter, it is essential to analyze the presence of harmful substances in car exhaust gases. The main harmful substances to look for include: 1. Carbon monoxide (CO): a toxic gas resulting from incomplete combustion of hydrocarbons. 2. Hydrocarbons (HC): unburned fuel molecules that can contribute to smog and health issues. 3. Nitrogen oxides (NOx): a group of pollutants that can contribute to smog, acid rain, and respiratory issues. An effective catalytic converter should reduce the presence of these harmful substances in the car exhaust.

Automobile catalytic converters must work at high temperatures because the chemical reactions they facilitate are more efficient and effective when carried out at higher temperatures. Advantages of high-temperature catalytic converters: 1. Increased efficiency: Higher temperatures enable faster and more complete reactions to reduce harmful emissions. 2. Faster activation: Catalytic converters reach their optimal operating temperature more quickly, which can help reduce cold-start emissions. Disadvantages of high-temperature catalytic converters: 1. Material degradation: The high temperatures can wear down the materials used in the converter, potentially decreasing its lifespan. 2. Overheating risks: High temperatures could cause surrounding components in the vehicle to overheat or even catch fire if not properly managed or insulated.

The rate of flow of exhaust gases over a catalytic converter is important because it affects the efficiency of the catalytic converter's function. If the flow rate is too high, the exhaust gases may pass through the converter too quickly, which can reduce the amount of contact time between the gases and the catalyst, decreasing the converter's efficiency. On the other hand, if the flow rate is too low, it could lead to increased backpressure in the exhaust system, which can negatively impact engine performance and efficiency. Finding an optimal flow rate helps to balance the effectiveness of the catalytic converter with the overall performance of the vehicle.