What is a mixture that has too much vapour to ignite called?

A mixture that has too much vapor to ignite is referred to as a rich mixture. This term is used to describe a mixture where the fuel concentration is higher than the ideal stoichiometric ratio with respect to oxygen. In this scenario, the abundance of fuel (vapor) means that there isn't enough oxygen available to achieve a successful ignition.

When conditions are such that the fuel-to-air ratio exceeds the optimal range, the immediate environment becomes too saturated with fuel vapor, preventing the formation of a combustible mixture with sufficient oxygen. Thus, while the presence of fuel is essential for combustion, an excess can actually hinder ignition, leading to the classification of the mixture as rich.

In contrast, a lean mixture has a fuel concentration that is below the ideal level, which could lead to combustion if there is enough oxygen present. Explosive and flammable mixtures imply the potential for ignition and explosive reactions, which is not considering a mixture that is saturated with vapor.