1 mole Ag107.87 grams Ag1870 grams Ag1×1 mole Ag107.87 grams Ag17.3 mole Ag201 grams Hg1 mole Hg0.004 moles Hg1×201 grams Hg1 mole Hg0.8 grams HgCHARACTERISTICS OF ATOMSDOE-HDBK-1015/1-93Fundamentals of ChemistryCH-01Rev. 0Page 10Example 1:A silver bar has a mass of 1870 grams. How many moles of silver are in the bar?Solution:Since the atomic mass of silver (Ag) is 107.87 amu, one mole of silver has a mass of107.87 grams. Therefore, there is one mole of Ag per 107.87 grams of Ag or. There are 1870 grams of silver. Example 2:Mercury (Hg) is the only metal that exists as a liquid at room temperature. It isused inthermometers. A thermometer contains 0.004 moles of mercury. How many grams ofmercury are in the thermometer?Solution:Since the atomic mass of Hg is 201 amu, one mole of Hg has a mass of 201 grams of Hgor . There are 0.004 moles of Hg.MoleofMoleculesThe mass of a mole of molecules ofa substance is the molecular mass expressed in grams. Forexample, an oxygen molecule (O) has a molecular mass equivalent to 32.0 grams because each2oxygen atom has a molecular mass of 16.0 grams. (Recall that to obtain the molecular mass, theatomic masses of all atoms that appear in the formula are added.) If the atomic masses of thecarbon and four hydrogen atoms in methane, CH , are added, the total is 16 amu. Therefore, one4mole of CH has a mass of 16 grams. The mass of a mole of molecules is called the molar mass4or gram molecular weight(GMW).
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