(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 assess the effectiveness of a catalytic converter, one would monitor the levels of the following substances in car exhaust: 1. Carbon monoxide (CO): A toxic gas produced during incomplete combustion in the engine. The catalytic converter is responsible for converting it to the less harmful carbon dioxide (CO₂). 2. Hydrocarbons (HC): Unburned fuel particles that escape from the engine into the exhaust. The catalytic converter should reduce these by oxidizing them to form carbon dioxide and water. 3. Nitrogen oxides (NOx): Produced when nitrogen and oxygen in the air react at high temperatures in the engine. The catalytic converter should reduce these to nitrogen gas (N₂) and oxygen gas (O₂).

Advantages of high working temperatures in a catalytic converter: 1. Faster reaction rates: Higher temperatures increase the rate of chemical reactions, meaning the converter can more efficiently reduce harmful emissions. 2. Better oxidation of hydrocarbons: High temperatures improve the oxidation of unburned hydrocarbon fuel particles, leading to the formation of carbon dioxide and water. Disadvantages of high working temperatures in a catalytic converter: 1. Material degradation: High temperatures may lead to the degradation and eventual failure of the materials used in the catalytic converter. 2. Overheating: Excessively high temperatures can cause damage to the car's exhaust system and surrounding components.

The rate of flow of exhaust gases over a catalytic converter is important for the following reasons: 1. Reaction efficiency: A proper flow rate ensures that the exhaust gases have enough contact time with the catalyst material, allowing for efficient conversion of harmful substances. 2. Temperature regulation: The flow rate also influences the temperature of the catalytic converter. If the flow is too slow, the converter may overheat, risking damage to the exhaust system. If the flow is too fast, the converter may not reach the required temperature for optimal conversion of harmful substances.