2-chlorobenzalmalononitrile (also called o-chlorobenzylidene malononitrile) (chemical formula: C₁₀H₅ClN₂) is the defining component of a "tear gas" commonly referred to as CS gas, which is used as a riot control agent. "CS gas" is actually an aerosol

Aerosol

Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...

 of a volatile

Volatility (chemistry)

In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...

 solvent

Solvent

A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...

 (a substance that dissolves other active substances and that easily evaporates with it) and 2-chlorobenzalmalononitrile, which is a solid compound at room temperature.