The phase of chlorine is dependent upon temperature and pressure, but it is a gas at room temperature and standard pressure. At standard pressure, chlorine liquefies at minus 29.15 degrees Fahrenheit and freezes at minus 149.76 degrees Fahrenheit.
Room-temperature chlorine is a greenish-yellow gas. When liquefied, chlorine is a clear amber color. Chlorine is a halogen. The pure form is primarily produced through the electrolysis of sodium chloride. It is an irritant that can burn the skin in its liquid form. The gas was first used as a weapon during World War I that could cause death within a few breaths.