Analytical Chemistry :: essays research papers

Analytical ChemistryAnalytical Chemistry is the branch of chemistry principally concernedwith determining the chemic patch of materials, which may be solids,liquids, gases, pure elements, compounds, or complex mixtures. In addition,chemical analysis can characterize materials but determining their molecularstructures and measuring much(prenominal) physical properties as pH, color, and solubility.Wet analysis involves the studying of substances that have been submerged in asolution and microanalysis uses substances in very small amounts.Qualitative chemical analysis is used to detect and identify one or moreconstituents of a sample. This process involves a wide variety of tests.Ideally, the tests should be simple, direct, and easily performed with unattachedinstruments and chemicals. Test results may be an instrument reading, andobservation of a physical property, or a chemical reaction. Reactions used inqualitative analysis may attempt to cause a characteristic color, odor,prec ipitate, or gas appear. Identification of an unknown substance isaccomplished when a known one is found with like properties. If none isfound, the uknown substance must be a newly identified chemical. Tests shouldnot use up excessive amounts of a material to be identified. intimately chemicalmethods of qualitative analysis require a very small amount of the sample.Advance instrumental techniques often use less than one millionth of a gram. Anexample of this is mass spectrometry.Quantitative chemical analysis is used to determine the amounts ofconstituents. Most work in analytical chemistry is quantitative. It is alsothe more or less difficult. In principle the analysis is simple. One measures theamount of sample. In practice, however, the analysis is often complicated byinterferences among sample constituents and chemical separations are necessaryto set apart tthe analyte or remove interfering constituents.The choice of method depends on a number of factors Speed, Cost,Accuracy , Convenience, Available equipment, Number of samples, Size of sample,Nature of sample, and Expected concentration. Because these factors are interrelated any final choice of analytical method involves compromises and itis impossible to specify a single best method to carry out a given over analysis inall laboratories under all conditions. Since analyses are carried out undersmall amounts one must be careful when dealing with miscellaneous materials.Carefullly designed sampling techniques must be used to obtan representativesamples.Preparing solid samples for analysis usually involves grinding to reduceparticle size and ensure homogeneity and drying. Solid samples are weighedusing an accurate analytical balance. Liquid or gaseous samples are measureedby volume using accurately calibrated glassware or flowmeters. Many, but notall, analyses are carried out on solutions of the sample. Solid samples thatare insoluble in water must be treated chemically to dissolve them without any