A glowing splint bursts into flames when exposed to an oxygen-rich environment because the abundance of oxygen accelerates the combustion reaction of the splint material. The higher the oxygen concentration is, the more vigorously the glowing splint bursts into flames.
The glowing splint test is a simple qualitative test that is commonly used to evaluate oxidizing gases. A splint is lit and left to burn for a few seconds. The flame is put out, leaving a glowing ember at the tip of the splint. This ember is brought in contact with a gas sample with an unknown oxidative, reductive or neutral nature. If the splint reignites when it is brought into contact with the gas, this indicates that the gas was oxidizing. The brightness and size of the reignited flame indicates the concentration of oxidizing gas that was present.
Nitrous oxide is another oxidizing gas that yields a positive response from the glowing splint test. If the ember on the splint is extinguished when it comes in contact with the test gas, this indicates that the gas is either inert or reductive. Argon is an example of an inert gas, while carbon monoxide is an example of a reducing gas.