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Chapter 8 Solutions

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  1. Chapter 8 Solutions 8.6Properties of Solutions

  2. Solutions Solutions • contain small particles (ions or molecules) • are transparent • do not separate, even by filtration or through a semipermeable membrane • do not scatter light

  3. Colloids Colloids • have medium-sized particles • cannot be separated by filtration • can be separated by semipermeable membranes • scatter light

  4. Examples of Colloids

  5. Suspensions Suspensions • have very large particles • settle out • can be separated by filtration • must be stirred to stay suspended Examples: blood platelets, muddy water, and calamine lotion

  6. Solutions, Colloids, and Suspensions

  7. Comparison of Solutions, Colloids, and Suspensions

  8. Learning Check A mixture that has solute particles that do not settle out but are too large to pass through a semipermeable membrane is called a 1) solution 2) colloid 3) suspension

  9. Solution A mixture that has solute particles that do not settle out but are too large to pass through a semipermeable membrane is called a 2) colloid

  10. Colligative Properties Colligative properties • are changes in the properties of a solvent when solute particles are added • depend on the number of solute particles in solution • involve the lowering of freezing point • involve an increase in the boiling point

  11. Freezing Point Lowering and Boiling Point Elevation When 1 mole of solute particles is added to 1000 g of water, the • freezing point of water decreases by 1.86 °C (from 0 °C to –1.86 °C) • boiling point of water increases by 0.52 °C (from 100 °C to 100.52 °C)

  12. Moles of Particles The number of moles of particles depends on the type of solute: • nonelectrolytes dissolve as molecules 1 mole of nonelectrolyte = 1 mole of particles in water • strong electrolytes dissolve as ions 1 mole of electrolyte = 2 to 4 moles of particles in water

  13. Effect of Solute Particles

  14. Learning Check A 1000-g sample of water contains 0.50 mole of Na3PO4. What are the new freezing point (FP) and boiling point (BP) of the solution? 1) FP 1.86 °C; BP 100.52 °C 2) FP 3.72 °C; BP 101.04 °C 3) FP 7.44 °C; BP 102.08 °C

  15. Solution A 1000-g sample of water contains 0.50 mole of Na3PO4. What are the new freezing point (FP) and boiling point (BP) of the solution? 2) FP 3.72 °C; BP 101.04 °C Na3PO4 3Na+ + PO43- 0.50 mole 1.5 moles 0.5 mole Total moles of solute = 2.0 moles FP = 0 °C – 2(1.86 °C) = 0 °C – 3.72 °C = –3.72 °C BP = 0 °C + 2(0.52 °C) = 0 °C + 1.04 °C = 101.04 °C

  16. Osmosis In osmosis, • water (solvent) flows from the lower solute concentration into the higher solute concentration • the level of the solution with the higher solute concentration rises • the concentrations of the two solutions become equal with time

  17. Example of Osmosis A semipermeable membrane separates a 4% starch solution from a 10% starch solution. Starch is a colloid and cannot pass through the membrane, but water can. What happens? semipermeable membrane 4% starch 10% starch H2O

  18. Example of Osmosis (continued) • The 10% starch solution is diluted by the flow of water out of the 4% solution, and its volume increases. • The 4% solution loses water, and its volume decreases. • Eventually, the water flow between the two becomes equal. 7% starch 7% starch H2O

  19. Osmotic Pressure Osmotic pressure • is produced by the solute particles dissolved in a solution • is the pressure that prevents the flow of additional water into the more concentrated solution • increases as the number of dissolved particles in the solution increases

  20. Learning Check A semipermeable membrane separates a 10% (m/v) starch solution (A) from a 5% (m/v) starch solution (B).If starch is a colloid, fill in the blanks in the statements below. 1. Solution ____ has the greater osmotic pressure. 2. Water initially flows from ___ into ___. 3. The level of solution ____ will be lower.

  21. Solution A semipermeable membrane separates a 10% (m/v) starch solution (A) from a 5% (m/v) starch solution (B). If starch is a colloid, fill in the blanks in the statements below. 1. Solution A has the greater osmotic pressure. 2. Water initially flows from B into A. 3. The level of solution B will be lower.

  22. Osmotic Pressure of the Blood Red blood cells • have cell walls that are semipermeable membranes • maintain an osmotic pressure that cannot change without damage occuring • must maintain an equal flow of water between the red blood cell and its surrounding environment

  23. Isotonic Solutions An isotonic solution • exerts the same osmotic pressure as red blood cells • is known as a “physiological solution” • of 5.0% (m/v) glucose or 0.9% (m/v) NaCl is used medically because each has a solute concentration equal to the osmotic pressure equal to red blood cells

  24. Hypotonic Solutions A hypotonic solution • has a lower osmotic pressure than red blood cells (RBCs) • has a lower concentration than physiological solutions • causes water to flow into RBCs • causes hemolysis (RBCs swell and may burst)

  25. Hypertonic Solutions A hypertonic solution • has a higher osmotic pressure than RBCs • has a higher concentration than physiological solutions • causes water to flow out of RBCs • causes crenation (RBCs shrink in size)

  26. Dialysis In dialysis, • solvent and small solute particles pass through an artificial membrane • large particles are retained inside • waste particles such as urea from blood are removed using hemodialysis (artificial kidney)

  27. Learning Check Indicate if each of the following solutions is 1) isotonic 2) hypotonic 3) hypertonic A. ____ 2% (m/v) NaCl solution B. ____ 1% (m/v) glucose solution C. ____ 0.5% (m/v) NaCl solution D. ____ 5% (m/v) glucose solution

  28. Solution Indicate if each of the following solutions is 1) isotonic 2) hypotonic 3) hypertonic A. _3_ 2% (m/v) NaCl solution B. _2_ 1% (m/v) glucose solution C. _2_ 0.5% (m/v) NaCl solution D. _1_ 5% (m/v) glucose solution

  29. Learning Check When placed in each of the following, indicate if a red blood cell will 1) not change 2) hemolyze 3) crenate A. ____ 5% (m/v) glucose solution B. ____ 1% (m/v) glucose solution C. ____ 0.5% (m/v) NaCl solution D. ____ 2% (m/v) NaCl solution

  30. Solution When placed in each of the following, indicate if a red blood cell will 1) not change 2) hemolyze 3) crenate A. _1_ 5%(m/v) glucose solution B. _2_ 1%(m/v) glucose solution C. _2_ 0.5%(m/v) NaCl solution D. _3_ 2%(m/v) NaCl solution

  31. Hemodialysis • When the kidneys fail, an artificial kidney uses hemodialysis to remove waste particles such as urea from blood.

  32. Learning Check Each of the following mixtures is placed in a dialyzing bag and immersed in pure water. Which substance, if any, will be found in the water outside the bag? A. 10% (m/v) KCl solution B. 5% (m/v) starch solution C. 5% (m/v) NaCl and 5% (m/v) starch solutions

  33. Solution Each of the following mixtures is placed in a dialyzing bag and immersed in pure water. Which substance, if any, will be found in the water outside the bag? A. 10%(m/v) KCl solution: KCl ( K+, Cl−) B. 5%(m/v) starch solution: None, starch is retained. C. 5%(m/v) NaCl and 5%(m/v) starch solutions: NaCl (Na+, Cl−) will be found in the water outside the bag, but the starch is retained inside the bag.