Scan_Doc0031 - in your car's lead storage battery (a...

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:: are two ways of indicating units that - me denominator. For example, ,'lTite g/cm 3 or g cm- 3 . Although se the former system here, the em is widely used. 1.8 Density' 25 Compound Density in g/cm 3 at 20°C Chloroform . Diethyl ether Ethanol Isopropyl alcohol Toluene 1.492 0.714 0.789 0.785 0.867 Which of these compounds is the most likely to be the main component of the compact disc cleaner? Solution To identify the unknown substance, we must determine its density. This can be done by using the definition of density: mass Density = volume 3 19.625 g = 0.7850 g/cm 25.00 ern" This density corresponds exactly to that of isopropyl alcohol, which is therefore the most likely main component of the cleaner. However, note that the density of ethanol is also very close. To be sure that the compound is isopropyl alcohol, we should run several more density experiments. (In the modern laboratory, many other types of tests could be done to distinguish between these two liquids.) SEE EXERCISES 1.61 AND 1.62 Besides being a tool for the identification of substances, density has many other uses. For example, the liquid
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Unformatted text preview: in your car's lead storage battery (a solution of sulfuric acid) changes density because the sulfuric acid is consumed as the battery discharges. In a fully charged battery, the density of the solution is about 1.30 g/cm". If the density falls below 1.20 g/cnr', the battery will have to be recharged. Density measurement is also used to determine the amount of antifreeze, and thus the level of protection against freezing, in the cooling system of a car. The densities of various common substances are given in Table 1.5. Table 1.5 Densities of Various Common Substances* at 20°C Substance Physical State Density (g/cm 3 ) Oxygen Hydrogen Ethanol Benzene Water Magnesium Salt (sodium chloride) Aluminum Iron Copper Silver Lead Mercury Gold Gas Gas Liquid Liquid Liquid Solid Solid Solid Solid Solid Solid Solid Liquid Solid 0.00133 0.000084 0.789 0.880 0.9982 1.74 2.16 2.70 7.87 8.96 10.5 11.34 13.6 19.32 * At 1 atmosphere pressure....
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This note was uploaded on 12/13/2010 for the course CHEM 2301 taught by Professor Bill during the Spring '10 term at South Texas College.

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