Nitrous oxide, commonly known as laughing gas, is a colorless and nonflammable gas at room temperature. It has a slightly sweet odor and taste.
It can be used as an oxidizer in a rocket motor. The advantages over other oxidizers is that it is non-toxic and, due to its stability at room temperature, easy to store and relatively safe to carry on a flight. Another benefit is that it can be readily decomposed to form breathing air. Its high density and low storage pressure enable it to be highly competitive with stored high-pressure gas systems.
In vehicle racing, nitrous oxide is often referred to as just "nitrous". It allows the engine to burn more fuel by providing more oxygen than air alone, resulting in a more powerful combustion. The gas itself is not flammable but it delivers more oxygen than atmospheric air by breaking down at elevated temperatures. One of the major problems with using nitrous oxide in a reciprocating engine is that it can produce enough power to damage or destroy the engine.
Nitrous oxide is approved for use as a food additive, specifically as an aerosol spray propellant. The gas has also shown some benefit in treating a number of addictions including alcohol withdrawal.
Nitrous oxide has been used for anesthesia in dentistry for over 100 years. Hospitals are also administering it as an anesthetic, but it is a weak general anesthetic and is generally not used alone. It is known as "laughing gas" due to the euphoric effects of inhaling it.