Chapter 13.3 : Concentration of Solutions


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Chapter 13.3 : Concentration of Solutions

  1. 1. Concentration of Solutions<br />Chapter 13.3<br />
  2. 2. Objectives<br />Given the mass of solute and volume of solvent, calculate the concentration of a solution<br />Given the concentration of a solution, determine the amount of solute in a given amount of solution<br />Given the concentration of a solution, determine the amount of solution that contains a given amount of solute<br />
  3. 3. Concentration<br />Measure of the amount of solute in a given amount of solvent or solution<br />Solutions<br />Dilute or concentrated<br />Dilute – relatively small amount of solute in a solvent<br />Concentrated – relatively large amount of solute in a solvent<br /><ul><li>Measure of the amount of solute in a given</li></li></ul><li>Molarity<br />Number of moles of solute in one liter of solution<br />M - Symbol<br />Written as 1 M NaOH<br />One molar solution of sodium hydroxide<br />One mole NaOH in 1 liter of solution<br />amount of solute (mol)<br />molarity = <br />volume of solution (L)<br />Units are mol/L<br />
  4. 4. Making a 0.500 M Solution of NaOH<br />Step 1: Determine mass needed<br />M = <br />0.500 M =<br />mol solute = <br /> mass of NaOH needed = 0.500 mol NaOH x<br />mol solute<br />L solution<br />mol solute<br />1.00 L<br />0.500 M<br />1.00 L<br />X<br />= 0.500 mol NaOH<br />40.0 g NaOH<br />1 mol NaOH<br />= 20.0 g NaOH<br /><ul><li>Step 2: Measure out 20.0 g NaOH using a balance</li></li></ul><li>Step 3: Add less than one Liter of water to a volumetric flask. <br />Step 4: Dissolve 20.0 g (0.500 mol) of NaOH in the water.<br />Step 5: Fill volumetric flask to the line. <br />
  5. 5. Practice Problems<br />You have 3.50 L of solution that contains 90.0 g of sodium chloride, NaCl. What is the molarity of that solution?<br />You have 0.8 L of a 0.5 M HCl solution. How many moles of HCl does this solution contain?<br />To produce 40.0 g of silver chromate, you will need at least 23.4 g of potassium chromate in solution as a reactant. All you have on hand in the stock room is 5 L of 6.0 M K2CrO4 solution. What volume of the solution is needed to give you the 23.4 g K2CrO4 need for the reaction?<br />
  6. 6. Molality<br />Concentration of a solution expressed in moles of solute per kilogram of solvent.<br />m - symbol<br />Written as 1 m solution of NaOH<br />One molal solution of sodium hydroxide<br />1 mol NaOH in 1 kg of solvent<br />moles solute (mol)<br />molality = <br />mass of solvent (Kg)<br />
  7. 7. Practice Problems<br />A solution was prepared by dissolving 17.1 g of sucrose (table sugar, C12H22O11) in 125 g of water. Find the molal concentration of this solution.<br />A solution of iodine, I2, in carbon tetrachloride, CCl4, is used when iodine is needed for certain chemical tests. How much iodine must be added to prepare a 0.489 m solution of iodine in CCl4 if 100.0 g of CCl4 is used?<br />