Definition and Examples of Speakers in Language Studies

Definition and Examples of Speakers in Language Studies In linguistics and communication studies, a speaker is one who speaks: the producer of an utterance.  In rhetoric, a speaker is an orator: one who delivers a speech or formal address to an audience. In literary studies, a speaker is a  narrator: one who tells a story.   Observations On Speakers The average adult English speaker has a vocabulary of around thirty thousand words and speaks ten to twelve sounds per second. Most of us in modern America, apart from the very solitary and the very garrulous, speak anywhere from 7,500 to 22,500 words a day. Grabbing these words, one every four hundred milliseconds on average, and arranging them in sequences that are edited and reviewed for grammar and appropriateness before theyre spoken requires a symphony of neurons working quickly and precisely. Pronouncing (or signing) words in any language requires that your brain coordinate with your body in order to turn the electricity of nerve impulses into waves of sound (or, if you sign, of gesture and motion). So far, scientists have been able to draw only simple models of how the control of language toggles back and forth between the brain and the body.(Michael Erard, Um, Slips, Stumbles, and Verbal Blunders, and What They Mean. Random House, 2008)Since native speakers of a language can not have memorized each phrase or sentence of their language, given that the set of phrases and sentences is infinite, their linguistic knowledge cannot be characterized as a list of phrases or sentences. . . . If a list of phrases is insufficient, then how can we characterize the native speakers linguistic knowledge? We will say that a speakers linguistic knowledge can be characterized as a grammar consisting of a finite set of rules and principles that form the basis for the speakers ability to produce and comprehend the unlimited number of phrases and sentences of the language.(Adrian Akmajian, et al., Linguistics: An Introduction to Language and Communication, 5th ed. MIT Press, 2001) We thus make a fundamental distinction between competence (the speaker-hearers knowledge of his language) and performance (the actual use of language in concrete situations). . . . A record of natural speech will show numerous false starts, deviations from rules, changes of plan in mid-course, and so on. The problem for the linguist, as well as the child learning the language, is to determine from the data of performance the underlying system of rules that have been mastered by the speaker-hearer and that he puts to use in actual performance.(Noam Chomsky, Aspects of the Theory of Syntax. MIT Press, 1965) Pronunciation: SPEE-ker Etymology: From the Old English, speak Source: Adrian Akmajian, et al., Linguistics: An Introduction to Language and Communication, 5th ed. MIT Press, 2001 Michael Erard, Um, Slips, Stumbles, and Verbal Blunders, and What They Mean. Random House, 2008 Noam Chomsky, Aspects of the Theory of Syntax. MIT Press, 1965

Gravimetric Analysis Definition

Gravimetric Analysis Definition Gravimetric analysis is a collection of  quantitative analysis laboratory techniques  based on the measurement of an analytes mass. One example of a  gravimetric analysis technique  can be used to determine the amount of an ion in a solution by dissolving a known amount of a compound containing the ion in a solvent to separate the ion from its compound. The ion is then precipitated or evaporated out of solution and weighed. This form of gravimetric analysis is called precipitation gravimetry. Another form of gravimetric analysis is volatization gravimetry. In this technique, compounds in a mixture are separated by heating them to chemically decompose the specimen. Volatile compounds are vaporized and lost (or collected), leading to a measurable reduction on the mass of the solid or liquid sample. Precipitation Gravimetric Analysis Example In order for gravimetric analysis to be useful, certain conditions must be met: The ion of interest must fully precipitate from solution.The precipitate must be a pure compound.It must be possible to filter the precipitate. Of course, there is error in such an analysis! Perhaps not all of the ion will precipitate. They may be impurities collected during filtration. Some sample may be lost during the filtration process, either because it passes through the filter or else is not recovered from the filtration medium. As an example, silver, lead, or mercury may be used to determine chlorine because these metals for insoluble chloride. Sodium, on the other hand, forms a chloride that dissolves in water rather than precipitates. Steps of Gravimetric Analysis Careful measurements are necessary for this type of analysis. Its important to drive away any water that may be attracted to a compound. Place an unknown in a weigh bottle that has its lid cracked open. Dry the bottle and sample in an oven to remove water. Cool the sample in a desiccator.Indirectly weigh a mass of the unknown in a beaker.Dissolve the unknown to produce a solution.Add a precipitating agent to the solution. You may wish to heat the solution, as this increases the particle size of the precipitate, reducing loss during filtration. Heating the solution is called digestion.Use vacuum filtration to filter the solution.Dry and weigh the collected precipitate.Use stoichiometry based on the balanced chemical equation to find the mass of the ion of interest. Determine the mass percent of the analyte by dividing the mass of analyte by mass of unknown. For example, using silver to find an unknown chloride, a calculation might be: Mass of dry unknown chloride: 0.0984Mass of AgCl precipitate: 0.2290 Since one mole of AgCl contains one mole of Cl- ions: (0.2290 g AgCl)/(143.323 g/mol) 1.598 x 10-3 mol AgCl(1.598 x 10-3)x(35.453 g/mol Cl) 0.0566 g Cl (0.566 g Cl)/(0.0984 g sample) x 100% 57.57% Cl in unknown sample Note lead would have been another option for the analysis. However, if lead had been used, the calculation would have needed to account for the fact one mole of PbCl2 contains two moles of chloride. Also note, error would have been greater using lead because lead is not completely insoluble. A small quantity of chloride would have remained in solution instead of precipitating.