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Concentration of Sol’n16-2. The amount of solute in a given amount of solvent or solution. THE MOLE. The mole is used to express the concentration of a solution. Concentrated sol’n contain large amounts of solute and small amnt of solvent
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Concentration of Sol’n16-2 The amount of solute in a given amount of solvent or solution
THE MOLE • The mole is used to express the concentration of a solution. • Concentrated sol’n contain large amounts of solute and small amnt of solvent • Dilute sol’n contain small amnts of solute and large amnts of solvent.
Molarity • If defined in terms of volume of soln, depends on T. • Molarity = moles of solute liters of solution • M = mol L
Example #1 • If a manufacturer prepares a soln from 10.0g of NaOH dissolved in enough solvent to make .10L of soln. What is the M of the cleaner? • 10gNaOH x 1mol NaOH = 2.5 mol/L .10L 40g NaOH • 2.5M
Mole Fraction • See Practice Worksheet #1
Making Dilutions • Diluting a solution reduces the number of moles of solute per unit volume, but it does not change the total number of moles of solute. • Moles of solute B4 dl = mols of solute after dl • M1V1= M2V2
Example #3 • How many mL of aqueous 2.0M MgSO4 solution must be diluted with water to prepare 100mL of aq. 0.40 M MgSO4? • M1 = 2.0M • M2= .40M • V1 = ??? • V2 = 100mL
Percent Solutions • Conc. of solution in % expresses the ration of the volume of solute to the volume of solution. • When both the solute and the solvent are liquids • Ex. 91% alcohol contains 91 mL of isopropyl alcohol (2-propanol) with enough water to make 100 mL of solution • %by Volume = volume of solute x 100 volume of soln
Example #4 • What is the percent volume of ethanol in the final solution when 85 mL of ethanol is diluted to a volume of 250mL with water? • A bottle of hydrogen peroxide is labeled 3%. How many mL of H2O2 are in a 400mL bottle of this solution?