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SOLUTIONS

Learn about the concepts of solutions, solubility, solvation, and concentration levels in this informative chapter. Explore factors that affect solubility and techniques for diluting solutions. Understand the calculation of molarity and molality.

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SOLUTIONS

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  1. SOLUTIONS Chapter 15

  2. Solution = homogeneous mixture • Solute = gets dissolved (minor component) • Solvent = dissolving agent (major component)

  3. A substance that dissolves in a solvent is said to be soluble. These two substances are miscible.

  4. A substance that does not dissolve in a solvent is insoluble. These two substances are immiscible.

  5. Page 454 in Book (See Table 15-1, p.454)

  6. Water is an excellent solvent. It is the “universal solvent.” Solutions made with water are called aqueous solutions. Movie:

  7. Water is polar and dissolves many ionic and polar substances.

  8. Solvation = the process of surrounding solute particles with solvent particles to form a solution. Solute particles must separate from one another and the solute and solvent particles must mix.

  9. Ionic compounds dissolves in waterbecause they have charges (polar). Animation: Dissolving table salt

  10. “Like dissolves like.” • Polar solutes dissolve in polar solvents • Nonpolar solutes dissolve in nonpolar solvents

  11. Polar covalent compounds dissolve in water; non-polar compounds do not dissolve in water.Sugar (glucose) is polar and dissolves in water.

  12. Factors that affect rate of solvation • Stirring the mixture • Increasing the surface area of the solute • Increasing the temperature of the solvent

  13. Solubility = maximum amount of solute that will dissolve in a given amount of solvent at a specified temperature and pressure • Saturated = maximum amount of solute is dissolved • Unsaturated = more solute can be dissolved • Supersaturated = contains more dissolved solute than a saturated solution at the same temperature.

  14. Factors that affect solubility • Increased Temperature – solubility of solids increases; solubility of gases decreases. • Increased Pressure – solubility of gases increases. (This process is called aeration) • Henry’s Law –at a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid.

  15. Ch.15.2- Solution Concentration • The concentration of a solution is a measure of how much solute is dissolved in a specific amount of solvent or solution. solute or solute solvent solution (solution = solute + solvent)

  16. Expressing Concentration • Concentration may be described qualitatively as concentrated or dilute.

  17. Concentration= solute or solute solvent solution

  18. Percent by Mass (p.463 #8) • What is the percent by mass of NaHCO3 in a solution containing 20 g NaHCO3 dissolved in 600 mL H2O? • Density of H2O = 1.00 g/mL • % by mass = 20 g x 100 = 3.2% 620 g

  19. Percent by Mass (p.463 #9) • You have 1500.0 g of a bleach solution. The percent by mass of the solute sodium hypochlorite, NaOCl, is 3.62%. How many grams of NaOCl are in the solution? • % Mass = mass solute x 100 mass solution 3.62 = x g X 100 1500.0 g x = 54.3 g NaOCl

  20. Percent by Volume (p.464 #12) • If you have 100.0 mL of a 30.0% aqueous solution of ethanol, what volumes of ethanol and water are in the solution? • % Volume = volume of solute x 100% volume of solution 30.0 % = x mL x 100 100.0 mL x = 30 mL ethanol 70 mL water

  21. Molarity (p.465 #14) • What is the molarity of an aqueous solution containing 40.0 g of glucose (C6H12O6) in 1.5 L of solution? • 1 mole C6H12O6 = 180.16 g • 40.0 g C6H12O6 x 1 mole = 0.222 mol 180.16 g • Molarity = 0.222 mol = 0.15 M C6H12O6 1.5 liter

  22. Molarity (p.465 #15) • What is the molarity of a bleach solution containing 9.5 g NaOCl per liter of bleach?

  23. Molarity (p.465 #16) • Calculate the molarity of 1.60 L of a solution containing 1.55 g of dissolved KBr.

  24. Molarity (p.466 #17) • How many grams of CaCl2 would be dissolved in 1.0 L of a 0.10 M solution of CaCl2?

  25. Molarity (p.466 #18) • A liter of 2M NaOH solution contains how many grams of NaOH?

  26. Molarity (p.466 #19) • How many grams of CaCl2should be dissolved in 500.0 mL of water to make a 0.20M solution of CaCl2?

  27. Molarity (p.466 #20) • How many grames of NaOH are in 250 mL of a 3.0M NaOH solution?

  28. Diluting Solutions- p.467 • In the laboratory, you may use concentrated solutions called stock solutions. • For example, concentrated hydrochloric acid (HCl) is 12 M. • You can dilute the stock solution by adding more solvent. • Would you still have the same number of moles of solute particles that were in the stock solution?

  29. Diluting Solutions- p.467 • Molarity (M) = moles solute liters solution • moles solute = Molarity x liters solution • Because the total number of moles of solute does not change during dilution, moles solute in stock solution = moles solute after dilution M1V1 = M2V2

  30. Diluting Solutions- p.468 #21 • What volume of a 3.00 M KI stock solution would you use to make 0.300 L of a 1.25 M KI solution?

  31. Diluting Solutions- p.468 #23 • If you dilute 20.0 mL of a 3.5 M solution to make 100.0 mL of solution, what is the molarity of the dilute solution?

  32. Molality- p.469 • Molality (m) = moles solute = moles solute kilogram solvent 1000 g solvent • What is the molality of a solution containing 10. 0 g Na2SO4 dissolved in 1000.0 g of water? • What is the molality of a solution containing 30.0 g of naphthalene dissolved in 500.0g of toluene?

  33. Mole Fraction- p.470

  34. Mole Fraction- p.470 #26 • What is the mole fraction of NaOH in an aqueous solution that contains 22.8% NaOH by mass?

  35. Mole Fraction- p.470 #27 • An aqueous solution of NaCl has a mole fraction of 0.21. What is the mass of NaCl dissolved in 100.0 mL of solution?

  36. Parts per million (ppm)

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