What is the effect of applying carb heat to the fuel/air mixture?

Applying carb heat to the fuel/air mixture enriches the mixture. This is primarily due to the fact that carburetor heat introduces warmer air into the carburetor, which decreases the density of the air entering the engine. Warmer air is less dense than cold air, which results in a lower air mass available for combustion at a given volume. As the air becomes less dense, the proportion of fuel in the mixture increases relative to the amount of air, thus enriching the mixture.

This enrichment helps in preventing and clearing icing that can form in the carburetor during flight, especially in cold and humid conditions. Ice formation can disrupt the flow of the fuel/air mixture, leading to engine performance issues or even power loss. Therefore, applying carb heat not only enriches the mixture but also plays a critical role in maintaining engine performance.