Estimating the Analytical and Surface Enhancement Factors in SERS

The surface-enhanced Raman scattering (SERS) capabilities of silver nanoparticles is studied in this experiment by estimating the their analytical enhancement  and surface enhancement factors. Students are introduced to the fundamentals of SERS.

The full citation is here: Pavel, I. E.; Alnajjar, K. S, Monahan, J. L, Stahler, A., Hunter, N. E., Weaver, K. M. Baker, J. D., Meyerhoefer, A. J., Dolson, D. A.  J. Chem. Educ. 2012, 89, 286–290 and a link to the article is provided below (subscription to the journal required).

http://dx.doi.org/10.1021/ed200156n

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Quantitative Investigations of Biodiesel Fuel

In this experiment students complete four tasks: monitoring the production of biodiesel by a transesterification of a commercial oil; quantifying mixtures of biodiesel and petroleum-based diesel; using a Karl-Fisher titration to determine the impact of water on the quantification of biodiesel; and determining the figures of merit for several IR sampling platforms.

The full citation is here: Ault, A. P.; Pomeroy, R.  J. Chem. Educ. 2012, 89, 243–247 and a link to the article is provided below (subscription to the journal required).

http://dx.doi.org/10.1021/ed101097n

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Chemistry in Microfluidic Channels

The April edition of the Journal of Chemical Education has an interesting experiment that introduces students to the fabrication of a microfluidic device. The device uses a simple Y-channel design. After fabricating the device, students can use it to explore laminar flow at the interface of fluids merging at the interface between the two channels, to observe an acid-base reaction at the  interface, and to observe the precipitation of CaCO3 crystals at the  interface.

The full citation is here: Chia, M. C.; Sweeny, C. M.; Odom, T. W. J. Chem. Educ. 2011, 88, 461–464 and a link to the article is provided below (subscription to the journal required).

Chemistry in Microfluidic Channels – Journal of Chemical Education (ACS Publications and Division of Chemical Education).

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What if There is no Quantitative Analysis Course?

What happens if an institution does not have a quantitative analysis course? Where are  students introduced to the concepts of analytical chemistry and the importance of analytical measurements? This post describes how one institution approached this when the needs of the curriculum required eliminating the Quantitative Analysis class.

With the rapid growth of biochemistry and its increasing importance in the undergraduate chemistry curriculum, finding space for biochemistry classes and topics is a challenge. At DePauw University — a small, wholly undergraduate, liberal arts college — the desire to provide all chemistry majors with an introductory course in biochemistry and the desire to create a biochemistry major lead us, in 2001, to significantly reinvent our curriculum. One “victim” of this reorganization was the traditional sophomore course in Quantitative Analysis.

To ensure that we continued to provide all students — both chemistry majors and biochemistry majors — with an introduction to analytical chemistry, we transformed our old second semester general chemistry course into a new course focusing on three essential ideas: thermodynamics, equilibria, and kinetics. In addition to these traditional topics, we built time into the class and the lab to introduce additional analytical content.

Although the classroom portion of the course — Chem 260: Thermodynamics, Equilibria, and Kinetics — focuses on the three primary topics, approximately two weeks of classes are set aside for data analysis exercises covering topics such as uncertainty in measurements, the statistical comparison of data sets, regression analysis and the modeling of data, and the handling of outliers.

The laboratory portion of Chem 260 is designed to introduce students to analytical measurements and the importance of thinking like an analytical chemist. The lab meets for 14 weeks, with each week consisting of a single three-hour lab. Students work in teams of three, with each team having an instrument suite consisting of a Vernier LabPro data interface with pH, oxidation-reduction potential, and temperature probes, a drop counter for titrations, and an Ocean-Optics USB-2000 visible spectrometer.

After completing several case studies on ethics in science, the students complete four one-week preliminary labs that introduce them to the instrumentation, software, and analytical techniques they will use later in the semester. The students then complete four two-week project-based labs. For each of these project-based labs the students are given a question to answer and a set of issues to consider—the students are responsible for designing an experiment that provides an answer to the lab’s question. A summary of the experiments is provided here:

Preliminary Experiments (and analytical concepts)

  1. Preparing Solutions
    1. uncertainty in measurements
    2. summary statistics
  2. Newton’s Law of Cooling
    1. fitting theoretical models to data
    2. significance testing
  3. Determination of Acetic Acid in Vinegar
    1. pH calibration and measurement
    2. acid-base titrations
    3. primary and secondary standards
  4. Characterizing an Oscillating Reaction
    1. Beer’s law
    2. external standardization
    3. boxcar filters and ensemble averaging

Project-Based Experiments (and questions to answer)

  1. Decomposition of H2O2
    1. What is ΔH for the reaction?
    2. Can you verify that Fe3+ is acting as a catalyst?
  2. Thermodynamics of Ca(OH)2 Solubility
    1. What are the values of ΔG, ΔH, and ΔS for the solubility reaction?
    2. How does temperature affect the solubility of Ca(OH)2?
  3. Acid Dissociation Constants of Organic Dyes
    1. What is the pKa value for your assigned dye?
  4. Kinetics of the Bleaching of Dyes
    1. What is the rate law for the reaction?
    2. How does the solution’s pH affect the reaction’s rate?

For additional details a PowerPoint presentation on DePauw’s analytical curriculum is available here and a copy of the lab manual for Chem 260 is available here.

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