Experiments for Modern Introductory Chemistry: The Temperature Dependence of Vapor Pressure

Kildahl, Nicholas K.; Berka, L. H.

doi:10.1021/ed072p258

Cited by 14 publications

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“…A notable omission from this group is diphosphanes (P 2 R 4 ) which contain a P-P bond whose strength (ca. 52 kcal mol −1 ) 22 is intermediate between S-S (ca. 62 kcal mol −1 ) 23 and Se-Se (ca.…”

Section: Introductionmentioning

confidence: 99%

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Radical-initiated P,P-metathesis reactions of diphosphanes: evidence from experimental and computational studies

et al. 2021

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Section: Introductionmentioning

confidence: 99%

“…62 kcal mol −1 ) 23 and Se-Se (ca. 40 kcal mol −1 ) 22 and therefore diphosphanes should be candidates for DCC.…”

Section: Introductionmentioning

confidence: 99%

Radical-initiated P,P-metathesis reactions of diphosphanes: evidence from experimental and computational studies

et al. 2021

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“…6 Usually, experiments to measure vapor pressure use complex experimental arrangements with several different connections between glass elements 7,8 or materials of restricted access, such as a mercury manometers, 9−15 vacuum pumps 16 or other similar devices, 17−19 containers cooled with liquid nitrogen, 20 and gas chromatographs. 21 These factors make it difficult to reproduce these experiments for educational purposes, and they make the experiments costly and noninteractive.…”

Section: ■ Introductionmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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A creative apparatus for use in a hands-on laboratory experiment that allows the visualization of the vapor pressure as a function of temperature is described in this paper. Inspired by homemade barometers and using simple materials that are easily accessible for teaching laboratories, a low-cost system for the establishment of the vapor-pressure curve was constructed and applied in deionized water and in car-radiator-additive samples (based on ethane-1,2-diol) at different concentrations. The system constructed proved to be efficient, simple, and quite robust and is applicable in teaching activities for comparing and visualizing vapor-pressure curves of different liquids. It can also be used to estimate the molar enthalpy of water vaporization. The main advantages and drawbacks of the apparatus created, the results obtained for liquid samples, and the evaluation of the ruggedness of this experiment are described throughout the text. The establishment of this system is the result of a project developed by first-year-undergraduate students along with postgraduate students and professors from the Bachelor’s Program of Science and Technology, hosted by the Universidade Federal do ABC, as part of the innovative course the Experimental Basis of Natural Sciences, a practical course which seeks to build knowledge through experimentation.

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“…Although the initial expense of buying GCs is significant, the small sample volumes required for GC analysis result in lower student exposure to potentially hazardous chemicals, and the short analysis time required for GC renders the technique applicable to introductory laboratories that have relatively large numbers of students. The number of published articles referring to use of GC in the introductory chemistry laboratory is small but is increasing (4)(5)(6)(7)(8)(9)(10)(11).…”

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confidence: 99%

Intermolecular Forces in Introductory Chemistry Studied by Gas Chromatography, Computer Models, and Viscometry

et al. 1998

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The important concept of intermolecular forces can be difficult for students to grasp. We teach about intermolecular forces by integrating traditional viscometry-based physical measurements with modern chromatographic analysis and use of computer-based molecular models. This experiment also introduces the theory of chromatographic separations and incorporates relevant "real-world" samples, methods, and techniques. The three-hour experiment is used in our firstterm introductory chemistry laboratories, in which the majority of enrolled students are science or engineering majors.Gas chromatography (GC) is a widely employed separation technique in industrial and research laboratories. There are numerous GC experiments in the literature for the college chemistry laboratory. Historically, most of these were intended for mid-to upper-level classes, such as organic chemistry and instrumental analysis (1-3). Although the initial expense of buying GCs is significant, the small sample volumes required for GC analysis result in lower student exposure to potentially hazardous chemicals, and the short analysis time required for GC renders the technique applicable to introductory laboratories that have relatively large numbers of students. The number of published articles referring to use of GC in the introductory chemistry laboratory is small but is increasing (4-11).This experiment demonstrates how differences in intermolecular forces allow chemists to separate and identify mixtures. As part of this experiment, students perform qualitative GC analyses of mixtures of n-alkanes and identify a liquid sample that simulates one collected at an arson scene. The task of solving a "crime" keeps the students interested and focused on the experiment; this type of determination of flammable mixtures is used in forensic chemistry laboratories and in other laboratory experiments (10, 12).The separation of the n-alkanes and "arson samples" in the GC column is based primarily on differences in London forces. To complement these data and to help students understand better how intermolecular forces affect the properties of compounds, a viscometry experiment and computer models are used. Students relate the observed viscosity of a few organic liquids to their structures and intermolecular forces in the liquid state. Computer modeling allows students to envision, on a molecule-by-molecule basis, three-dimensional structure and polarity. Experimental Conditions MaterialsAll chemicals were purchased from Aldrich or Fisher Scientific and used without further purification. Gasoline, paint thinner, and charcoal lighter fluid were purchased from local merchants. Gas ChromatographyThe two gas chromatographs used for this experiment are identical Perkin Elmer Autosystems; each is equipped with a flame ionization detector and a 15-m fused-silica capillary column with an inner diameter of 0.32 mm and a methyl silicone film thickness of 1.0 µm. Both GCs have been adjusted to yield consistent and comparable results.The temperature program used begins at 70...

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Experiments for Modern Introductory Chemistry: The Temperature Dependence of Vapor Pressure

Cited by 14 publications

References 0 publications

Radical-initiated P,P-metathesis reactions of diphosphanes: evidence from experimental and computational studies

Radical-initiated P,P-metathesis reactions of diphosphanes: evidence from experimental and computational studies

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

Intermolecular Forces in Introductory Chemistry Studied by Gas Chromatography, Computer Models, and Viscometry

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