Chlorine is an elen1ental chenucal tImt exists as a gas at alnbient conditions but liquefies at moderate pressures. Some of its common physical properties are listed in Table 8.1.1. Chlorine is slightly water soluble, is yellow-green in the gaseous state, and has a strong characteristic odor. Because chlorine gas is about 2.5 times denser than air, it tends to stay close to the ground when released into tIle atInosphere. Liquid chlorine has a clear mnber color; one volume of liquid can vaporize to about 460 volumes of gas. In addition, liquid chlorine has a large coefficient of thermal expansion.