The boiling point is defined as “the temperature at which a liquid’s vapor pressure equals the pressure of the atmosphere on the liquid.” If the pressure is exactly 1 atmosphere (101,325 Pa), the temperature is referred to as “the normal boiling point.” Pure chemicals have a unique boiling point, and this fact can be used in some laboratory investigations to check on the identity and/or purity of a material. Mixtures of two or more compounds have a boiling point range. This chapter focuses on the estimation of boiling points for pure compounds only.