EXAMPLE3.6Juglone3.4Molar Mass85molecules, we need a special name for the fundamental unit of these materials. Insteadof molecule, we use the termformulaunit.Thus CaC03is the formula unit for calciumcarbonate, and NaCl is the formula unit for sodium chloride.Juglone, a dye known for centuries, is produced from the husks of black walnuts. It is alsoa natural herbicide (weed killer) that kills off competitive plants around the black walnut treebut does not affect grass and other noncompetitive plants. The formula forjuglone isCjQH603•a.Calculate the molar mass of juglone.b.A sample of 1.56X10-2g of pure juglone was extracted from black walnut husks.How many moles of juglone does this sample represent?Solutiona.The molar mass is obtained by summing the masses of the component atoms. In1moleofjuglone there are 10moles of carbon atoms, 6moles ofhydrogen atoms, and 3molesof oxygen atoms:10C: 10X12.01 g=120.1 g6 H:6X1.008g=6.048g30:3X16.00g=48.00gMass of 1mol ClOH603=174.1 gThe mass of 1mole of juglone is 174.1 g, which is the molar mass.b.The mass of 1mole of this compound is 174.1 g; thus 1.56
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