Vardner, J. and Loose, B. (2016). Molecular diffusion of CF3SF5 in pure water and artificial seawater. Marine Chemistry, 120, doi:10.1016/j.marchem.2016.01.005. “http://looselab.gso.uri.edu/wp-content/uploads/2016/04/Vardner-Loose-2016.pdf“
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Preparing a New Standard Gas to Find the Diffusion Coefficients
by Jon Vardner •
We decided to prepare a new standard gas since the old standard gas was giving us variable, inaccurate results. We decided to target a standard gas with CF3SF5, SF6, and N2O concentrations of 119 ppmv, 476 ppmv, and 4% respectively. We…
Calculating the Diffusion Coefficients
by Jon Vardner •
At steady state, the flux across the water barrier took the form of Fick’s First Law. Since the solubility of CF3SF5 in water was estimated by Ho and Smethie Jr. (2008), the flux was rewritten in terms of the gas solubility…
Finding the Concentration of the Triple Standard
by Jon Vardner •
The concentration of the triple standard was very high. Therefore to find its concentration, we had to dilute the standard gas, measure the concentration of the diluted gas, and then account for the dilution step. First, we accurately measured the…
Diffusing the Gas and Measuring its Concentration
by Jon Vardner •
We diffused the standard gas through agar gel rather than water. Agar gel provides support for the water barrier without strongly influencing diffusion through it. The effects of diffusing gas through agar rather than water are well documented. We decided…
Making a Calibration Curve
by Jon Vardner •
Next, we made a calibration curve so that we could find the unknown concentrations for SF6 and CF3SF5 in our triple standard. To make the calibration curve, we needed to find the area under the peak in the chromatogram at…
Restoring the GC
by Jon Vardner •
We restored the Gas Chromatograph (GC) after a year long hiatus. The GC took a while to warm up, but thankfully it started running after a few days. Here’s a picture of the GC that we used. After the GC warmed up,…
Making the Triple Standard: N20, SF6, and CF3SF5
by Jon Vardner •
The first step of the project was making the triple standard gas containing N20, SF6, and CF3SF5. We needed CF3SF5 in the cocktail so that we could find its diffusion coefficient (the purpose of the experiment). We added N20 and SF6…