What does an increased stoichiometric ratio indicate?

An increased stoichiometric ratio indicates less fuel relative to air in a combustion process. The stoichiometric ratio refers to the ideal proportion of fuel to air that achieves complete combustion. When this ratio increases, it means that the amount of air supplied is greater compared to the amount of fuel. A higher stoichiometric ratio signifies that there is an excess of air, leading to a leaner fuel mixture. This condition can improve combustion efficiency and reduce emissions, as there is more oxygen available for the fuel to combust fully.

In practice, operating with a higher stoichiometric ratio typically allows for more complete burning of the fuel, resulting in fewer unburned hydrocarbons and pollutants in the exhaust. This principle is crucial in optimizing combustion systems, as the ideal mixture for promoting efficient fuel use is critically dependent on maintaining appropriate air-to-fuel ratios.

The other options do not accurately describe the significance of an increased stoichiometric ratio. For instance, more fuel relative to air and a richer fuel mixture suggest less oxygen, which contradicts the concept of an increased ratio. Complete combustion can be achieved at the correct stoichiometric ratio, but an increase beyond that yet would not imply completeness by itself; the context of fuel availability must be considered.