A new vapor pressure model containing one parameter is presented. The vapor pressure curves of all hydrocarbons that may contain heteroatoms merge together at a common point. Thus, the vapor pressure curve can be predicted using one known data point. If no data are available, the characteristic parameter can be obtained using structural information about the component. Since vapor pressure curves end in their critical points, the equation allows internally consistent prediction of critical pressure from known critical temperature, or vice versa, and for predicting the acentric factor. For calculating the heat of vaporization at any temperature using the Clapeyron equation, knowledge of the nonideal behavior of a component along the vapor pressure curve is needed. The equations presented for this purpose show excellent agreement for all components for which experimental data have been found.