phychem lab rep 2 - EXPERIMENT NO. 1 DETERMINATION OF MOLAR...

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EXPERIMENT NO. 1 DETERMINATION OF MOLAR MASS OF A VOLATILE LIQUID BY VAPOR-DENSITY METHOD GROUP NO. 2 CABUNGCAL, Ma. Andrea Danita E. ChE -2 / 2008140407 Abstract This Final Report discusses about the principles we had applied regarding the gas laws and determination of the molar mass of organic compounds. It explains how the molecular structure of a substance greatly contributes to the vapor density measured. I had also included the procedures we did and the list of apparatuses we used. At the end of this report, the table for our data is found. Based from the data, we had encountered slight differences or inconsistencies that are why we altered some of the values and corrected the procedures for our experiment. The list of references is also included in this report where we relied on for literature. Introduction In this experiment, we should be able to determine and estimate the molar mass of the three volatile liquid samples from their vapor densities at a temperature above their boiling points using the Dumas method. The Dumas method is still used in various chemistry subjects, customarily in analytical and physical chemistry. In analytical chemistry, the method was used for the quantitative determination of Nitrogen in chemical substances. It involves the combustion of a sample of known mass in a high temperature about 900 ° C with the presence of Oxygen. This leads to the release of carbon dioxide, water and nitrogen. The gases are then passed over special columns that absorb the carbon dioxide and water. A column containing a thermal conductivity detector at the end is then used to separate the nitrogen from any residual carbon dioxide and water and the remaining nitrogen content is measured. The instrument must first be calibrated by analyzing a material that is pure and has a known nitrogen concentration. The measured signal from the thermal conductivity detector for the unknown sample can then be converted into nitrogen content. As with the
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EXPERIMENT NO. 1 DETERMINATION OF MOLAR MASS OF A VOLATILE LIQUID BY VAPOR-DENSITY METHOD GROUP NO. 2 CABUNGCAL, Ma. Andrea Danita E. ChE -2 / 2008140407 Kjeldahl method, conversion of the concentration of nitrogen in a sample to the crude protein content is performed using conversion factors which depend on the particular amino acid sequence of the measured protein. The Dumas method has the advantages of being easy to use and automate. It is also considerably faster than the Kjeldahl method, taking a few minutes per measurement, as compared to the hour or more for Kjeldahl. It also does not make use of toxic chemicals or catalysts. One major disadvantage is its high initial cost. Also, as with Kjeldahl, it does not give a measure of true protein, as it registers non-protein nitrogen in addition. Also, as with Kjeldahl, different correction factors are needed for different proteins because they have different amino acid sequences. Finally, the small sample size raises the risk of obtaining an unrepresentative sample. On the other hand, the Dumas method regarding vapor densities involves finding
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phychem lab rep 2 - EXPERIMENT NO. 1 DETERMINATION OF MOLAR...

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