Using Conductivity Measurements To Determine the Identities and Concentrations of Unknown Acids: An Inquiry Laboratory Experiment
K. Christopher Smith and Ariana Garza, J. Chem. Educ., Article ASAP (As Soon As Publishable), Publication Date (Web): May 8, 2015
This article describes a student-designed titration experiment that uses LabQuest and a Conductivity Probe to identify unknown acids as being either HCl or H2SO4 and to determine the concentrations of the acids. Using an inquiry context, students gain experience with titrations, conductivity, procedural design, and analysis of results. The experiment is suitable for advanced high school or college-level general chemistry students.
Decay Kinetics of UV-Sensitive Materials: An Introductory Chemistry Experiment
Garrhett Via, Chelsey Williams, Raymond Dudek, and John Dudek, J. Chem. Educ. 2015, 92, 747–751
A procedure that provides an innovative approach to undergraduate chemistry kinetics experiments is described in this article. Logger Pro and a SpectroVis Plus Spectrophotometer with the SpectroVis Optical Fiber are used to measure the reflection spectrum from an incandescent bulb off of a UV-sensitive bead or thread, both in its excited state (immediately after UV irradiation) and unexcited state (only incandescent illumination). First-order kinetic decay rates are obtained by measuring the time- dependent reflection spectra of ultraviolet sensitive objects as they return from their excited, colored state back to their ground, colorless state.
Demonstrations of Frequency/Energy Relationships Using LEDs
Graham T. Cheek, J. Chem. Educ. 2015, 92, 1049–1052
In this article, the use of LEDs (light-emitting diodes) to demonstrate the relationship between frequency (or wavelength) and semiconductor energy level differences is described. LEDs can function as light detectors, and this ability is exploited to show the minimum light frequency needed to produce a voltage response in an LED. The light sources can be other LEDs or a flashlight with colored filters. A SpectroVis Plus Spectrophotometer with a SpectroVis Optical Fiber was used to measure visible LED wavelengths when nominal values were not available.
Boiling Water Demo: Much More than Meets the Eye
Jean Weaver, Chem13 News, 2015, 415, 8–9
This article presents a demonstration to help students understand what happens at the microscopic level when water warms and boils. The setup uses Logger Pro and a Stainless Steel Temperature Probe to monitor the temperature of a beaker of water heated by a hot plate. The author explains how the activity allowed students to think critically about the relationship between kinetic energy, potential energy, heat, and temperature.