| 单词 | empirical formula |
| 例句 | In the last step, realize that the smallest whole number ratio is the empirical formula: Chemistry 2019-02-14T00:00:00Z The value of k, however, does not keep constant so satisfactorily in the case of highly dissociated substances, and empirical formulae have been constructed to represent the effect of dilution on them. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" 2011-01-29T03:00:23.777Z In other words, twenty-four different compounds, all having the same empirical formula and similar sugar-like properties are theoretically possible. The Chemistry of Plant Life The typical cellulose is represented by the empirical formula C6H10O5, identical with that of starch, with which it has many chemical analogies as well as physiological correlations. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 5 "Cat" to "Celt" Formulae which merely express the relative number of atoms of the different elements present in a compound are termed empirical formulae, and the formulae of all compounds whose molecular weights are undetermined are necessarily empirical. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 1 "Châtelet" to "Chicago" The molecular formula is thus derived from the empirical formula by multiplying each of its subscripts by three: Chemistry 2019-02-14T00:00:00Z But so far as we could learn, the marine engineers possessed only empirical formulas, and the exact action of the screw-propeller, after a century of use, was still very obscure. The Early History of the Airplane Ordinary resin, or colophony, consists chiefly of a monobasic acid having the empirical formula C20H30O2, known as sylvinic acid, whose exact structure is not known. The Chemistry of Plant Life The sum of these quantitative data is inconsistent with a pentose or pentosane formula; it is more satisfactorily expressed by the empirical formula which represents a pentose monoformal. Researches on Cellulose 1895-1900 Guetta is himself evidently at a loss to grasp the significance of the empirical formula, "Listen and imitate." The Psychology of Singing A Rational Method of Voice Culture Based on a Scientific Analysis of All Systems, Ancient and Modern A compound’s percent composition provides the mass percentage of each element in the compound, and it is often experimentally determined and used to derive the compound’s empirical formula. Chemistry 2019-02-14T00:00:00Z However, since it was impossible to determine the molecular weight, he could not say what the gas was, save that the empirical formula was C62TH H39O27N5. The Black Star Passes We offer these views, however, only as suggestions to others more competent to grapple with the question, as promising a satisfactory solution of Bode’s empirical formula. Outlines of a Mechanical Theory of Storms Containing the True Law of Lunar Influence In this and its properties it appeared to be identical with the product isolated by Cross and Bevan from jute, with the empirical formula C19H18Cl4O9. Researches on Cellulose 1895-1900 But, so far as we could learn, the marine engineers possessed only empirical formulae, and the exact action of the screw propeller, after a century of use, was still very obscure. A History of Aeronautics Thus, they often have relatively simple empirical formulas. Chemistry 2019-02-14T00:00:00Z In this case, one mole of empirical formula units and molecules is considered, as opposed to single units and molecules. Chemistry 2019-02-14T00:00:00Z Finally, derive the molecular formula for nicotine from the empirical formula by multiplying each subscript by two: Chemistry 2019-02-14T00:00:00Z Comparing the molar mass to the empirical formula mass shows how many empirical formula units make up a molecule: Chemistry 2019-02-14T00:00:00Z What is the empirical formula of the xenon fluoride in the original sample? Chemistry 2019-02-14T00:00:00Z What is the empirical formula of the compound of silver and carbon? Chemistry 2019-02-14T00:00:00Z What is the empirical formula of the compound? Chemistry 2019-02-14T00:00:00Z What is the empirical formula of this compound? Chemistry 2019-02-14T00:00:00Z To derive the empirical formula of the compound, only the subscripts x and y are needed. Chemistry 2019-02-14T00:00:00Z With these molar amounts, the empirical formula for the compound may be written as described in the previous chapter of this text. Chemistry 2019-02-14T00:00:00Z Note that a molecular formula is always a whole- number multiple of an empirical formula. Chemistry 2019-02-14T00:00:00Z The empirical formula for the compound is then derived by identifying the smallest whole-number multiples for these molar amounts. Chemistry 2019-02-14T00:00:00Z What is the empirical formula of the black tungsten chloride? Chemistry 2019-02-14T00:00:00Z What is the empirical formula for this compound? Chemistry 2019-02-14T00:00:00Z There are four zinc ions and four sulfide ions in the unit cell, giving the empirical formula ZnS. Chemistry 2019-02-14T00:00:00Z What are the molecular and empirical formulas of glucose? Chemistry 2019-02-14T00:00:00Z If 0.0923 g of silicon reacts with sulfur to give 0.3030 g of silicon sulfide, determine the empirical formula of silicon sulfide. Chemistry 2019-02-14T00:00:00Z Determine the empirical formula for the white solid and write balanced chemical equations for the reactions involving xenon. Chemistry 2019-02-14T00:00:00Z However, the formulas for some ionic compounds containing polyatomic ions are not empirical formulas. Chemistry 2019-02-14T00:00:00Z The subscripts in this formula are not the smallest-possible whole numbers, as each can be divided by 2 to yield the empirical formula, NaCO2. Chemistry 2019-02-14T00:00:00Z The simplest whole-number ratio of C to H to O atoms in glucose is 1:2:1, so the empirical formula is CH2O. Chemistry 2019-02-14T00:00:00Z An empirical formula gives the simplest, whole-number ratio of atoms in a compound. Chemistry 2019-02-14T00:00:00Z As long as the molecular or empirical formula of the compound in question is known, the percent composition may be derived from the atomic or molar masses of the compound's elements. Chemistry 2019-02-14T00:00:00Z These molar amounts are used to compute whole-number ratios that can be used to derive the empirical formula of the substance. Chemistry 2019-02-14T00:00:00Z Consider as another example a sample of compound determined to contain 5.31 g Cl and 8.40 g O. Following the same approach yields a tentative empirical formula of: Chemistry 2019-02-14T00:00:00Z The molecular formula is then obtained by multiplying each subscript in the empirical formula by n, as shown by the generic empirical formula AxBy: Chemistry 2019-02-14T00:00:00Z In this case, dividing by the smallest subscript still leaves us with a decimal subscript in the empirical formula. Chemistry 2019-02-14T00:00:00Z To convert this into a whole number, multiply each of the subscripts by two, retaining the same atom ratio and yielding Cl2O7 as the final empirical formula. Chemistry 2019-02-14T00:00:00Z What is the empirical formula for this gas? Chemistry 2019-02-14T00:00:00Z Coefficients for the tentative empirical formula are derived by dividing each molar amount by the lesser of the two: Chemistry 2019-02-14T00:00:00Z For example, consider a covalent compound whose empirical formula is determined to be CH2O. Chemistry 2019-02-14T00:00:00Z Since the resulting ratio is one carbon to two oxygen atoms, the empirical formula is CO2. Chemistry 2019-02-14T00:00:00Z Determining the absolute numbers of atoms that compose a single molecule of a covalent compound requires knowledge of both its empirical formula and its molecular mass or molar mass. Chemistry 2019-02-14T00:00:00Z Molecular formulas are derived by comparing the compound’s molecular or molar mass to its empirical formula mass. Chemistry 2019-02-14T00:00:00Z As the name suggests, an empirical formula mass is the sum of the average atomic masses of all the atoms represented in an empirical formula. Chemistry 2019-02-14T00:00:00Z If the compound’s molecular mass is determined to be 180 amu, this indicates that molecules of this compound contain six times the number of atoms represented in the empirical formula: Chemistry 2019-02-14T00:00:00Z As the first step, use the percent composition to derive the compound’s empirical formula. Chemistry 2019-02-14T00:00:00Z Comparing the molar mass and empirical formula mass indicates that each nicotine molecule contains two formula units: Chemistry 2019-02-14T00:00:00Z The empirical formula mass of a covalent compound may be compared to the compound’s molecular or molar mass to derive a molecular formula. Chemistry 2019-02-14T00:00:00Z This line spectrum was simple enough that an empirical formula called the Rydberg formula could be derived from the spectrum. Chemistry 2019-02-14T00:00:00Z Molecules of this compound are then represented by molecular formulas whose subscripts are six times greater than those in the empirical formula: Chemistry 2019-02-14T00:00:00Z |
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