Lab 4_ Gas Chromatography (GC) Analysis of Hydrocarbons (1)

In a common laboratory experiment in general chemistry, students are asked to determine the relative amounts of benzoic acid and charcoal in a solid mixture. Benzoic acid is relatively soluble in hot water, hut charcoal is not. Devise a method for separating the two components of this mixture

Gas chromatography is an analytical technique that is used to separate and analyze samples that can be vaporized without decomposing. The chromatography column contains a substance that helps separate the sample being analyzed. The sample is vaporized and carried through the column by an inert gas. As the mixture moves through the column, the compounds are separated based on how much they interact with the substance in the column. The molecules of each compound are detected as they exit the column, and a peak for each compound is produced on a chromatogram. The area under each peak on the chromatogram is proportional to the concentration of the compound in the sample. A chromatogram produced by separating a mixture of compounds is shown. Time to Go Through Column Based on the information given, which of the following statements about the chromatogram is most likely true? A The three peaks each represent a different element. B The three peaks each represent a different substance used to…

Crime scene investigators keep a wide variety of compounds on hand to help with identifying unknown substances they find in the course of their duties. One such investigator, while reorganizing their shelves, has mixed up several small vials and is unsure about the identity of a certain powder. Elemental analysis of the compound reveals that it is 67.31 % carbon, 6.978% hydrogen, 4.617% nitrogen, and 21.10% oxygen by mass.     Which of the compounds could the powder be? C17H19NO3C17H19NO3 = morphine, analgesic C17H21NO4C17H21NO4 = cocaine, illicit drug C7H5N3O6C7H5N3O6 = 2,4,6-trinitrotoluene (TNT), commonly used explosive C10H15NC10H15N = methamphetamine, stimulant C4H5N2OC4H5N2O = caffeine, stimulant C11H15NO2C11H15NO2 = 3,4-methylenedioxymethamphetamine (MDMA), illicit drug C21H23NO5C21H23NO5 = heroin, illicit drug C3H6NO3C3H6NO3 = hexamethylene triperoxide diamine (HMTD), commonly used explosive

About Sampling, tick only the incorrect alternative(s). Choose one or more: A) Identifying the nature of a substance present in an unknown sample is called qualitative analysis. The process of measuring how much a constituent is present in a substance is called quantitative analysis. B) A type of error that is known due to procedures that cause a measure to be too large or too small is called a random error, such as reading a scale. C) Sample preparation is the process in which a representative sample is converted into a form suitable for chemical analysis. This usually means dissolving the sample. For a sample with low analyte concentration it may need to be diluted before being analyzed. D) Sampling is the process used to collect a representative sample for analysis. As real abnormals, as regulators are used in real experiments, they also typically prepare some degree of sample preparation to remove substances that do not interfere with the analysis of the desired analyte and…

In Part A you will be performing several mass measurements. What are two precautions you must observe when using the electronic balance?

What problems of society can analytical chemists help in finding solutions? How do they do it?   Discuss the quartering method of sampling.