The vapor pressure (VP) as a function of temperature of a pure VOC or homogeneous binary VOC mixture can readily be measured using an ebulliometer. The VP is also known in the literature as the “Bubble Point Pressure.” In this investigation, the VP as a function of temperature was acquired for the VOCs ethanol, iso-octane (2,2,4-trimethylpentane) and n-heptane. The latter two VOCs are the major components found in 87, 89, and 92 grade gasoline. Ethanol is an oxygenate additive of gasoline. The VP of a homogeneous binary mixture of iso-octane and n-heptane was also acquired using the same ebulliometer and methodology. The binary mixture served as a proxy 87 grade gasoline. An enhanced ebulliometer was used to collect the VP data and is known as the vapor pressure acquisition system (VPAS). The devices that comprise the system automatically and rapidly collect data in a highly efficient approach that is logged into an excel spreadsheet. From here, the stored data can be readily transformed into information to compute the heat of vaporization and other thermodynamic quantities. The results described in this investigation of the proxy gasoline mixture compared quite favorably to the literature values of the enthalpy of vaporization for gasoline. This strengthens the validity of our system for performing fast and reliable VP measurements in this area of research.

Computing the enthalpy of vaporization of ethanol, n-Heptane, isooctane, and a homogeneous binary mixture of Isooctane + n-heptane from their vapor pressure data

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.