Vapor pressure apparatus for general chemistry

Abstract

A simple apparatus for collecting vapor pressure data; relies on a mercury manometer.

Determination of Enthalpy of Vaporization of Pure Liquids by UV Spectrometry

“…According to eq 4, by measuring the vapor absorbance as a function of the temperature, AHv can be obtained from the slope of a plot of In A vs. 1IT. The constant k that relates absorbance to vapor pressure can be evaluated by comparing eq 4 with eq 3 and fitting eq 3 with data of the vapor pressure as a function of the temperature reported in the literature (9)(10)(11) or measured with one of the earlier reported methods (4)(5)(6)(7)(8). Assuming ideal behavior for the vapor, we can estimate the molar absorptivity of the organic product in the vapor phase from the absorbance and vapor pressure values at a given temperature.…”

“…The Clausius-Clapeyron equation integrated for liquidvapor equilibrium is introduced to describe the variation of vapor pressure with the temperature and to determine the enthalpy of vaporization. Several demonstrations involving the volatility of liquids (1)(2)(3) and methods of measuring the change in vapor pressure with change in temperature have been reported in this Journal (4)(5)(6)(7)(8). In all of them, the measurement of the vapor pressure was achieved by measuring the pressure of the vapors on liquids using several types of manometers.…”

Creating and Experimenting with a Low-Cost, Rugged System to Visually Demonstrate the Vapor Pressure of Liquids as a Function of Temperature

“…Most experiments demonstrating the behavior of the vapor pressure of liquids as a function of temperature are based on the isoteniscope. − Designed specifically for this purpose, the isoteniscope provides a standard method widely used for accurate and precise establishment of the vapor-pressure curves of different liquids . Usually, experiments to measure vapor pressure use complex experimental arrangements with several different connections between glass elements , or materials of restricted access, such as a mercury manometers, − vacuum pumps or other similar devices, − containers cooled with liquid nitrogen, and gas chromatographs . These factors make it difficult to reproduce these experiments for educational purposes, and they make the experiments costly and noninteractive.…”

An Inexpensive Microscale Method for Measuring Vapor Pressure, Associated Thermodynamic Variables, and Molecular Weight

“…Simply from measurements of vapor pressure one can learn thermodynamics, solution chemistry, intermolecular bonding, the chemistry of gases, and the determination of molecular weight (1). This versatility has led to the perennial publication, in these pages, of methods for measuring vapor pressure (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). However, even the simplest of these methods (2,14 ) is too expensive for use in a large urban high school like ours, while existing microscale methods (17) are not sufficiently quantitative.…”