What effect does applying carburetor heat have on the fuel/air mixture?

Applying carburetor heat enriches the fuel/air mixture. When carburetor heat is applied, hot air from the engine is introduced into the carburetor, which raises the temperature of the incoming air. This hot air is less dense than the cooler ambient air, therefore it has a lower oxygen content. As a result, the same amount of fuel is mixed with a smaller volume of air, which causes the mixture to become richer (a higher fuel-to-air ratio). This is particularly useful during conditions such as low temperatures, where ice may form in the carburetor, potentially disrupting the flow of air into the engine. Enriching the mixture helps to prevent issues related to icing and ensures smoother engine operation.

This understanding is essential for pilots and aviation professionals to maintain engine performance and reliability under various operational conditions.