9 6 Properties of Solutions Ethylene glycol is

9. 6 Properties of Solutions Ethylene glycol is added to a radiator to form an aqueous solution that has a lower freezing point than water. Learning Goal Identify a mixture as a solution, a colloid, or a suspension. Describe how the number of particles in a solution affects the freezing point, the boiling point, and the osmotic pressure of a solution. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Solutions or Colloids Solutions • are transparent. • do not separate. • contain small particles, ions, or molecules that cannot be filtered and pass through semipermeable membranes. Colloids • have medium-sized particles. • cannot be filtered. • can be separated by semipermeable membranes. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Examples of Colloids General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Suspensions • are heterogeneous, nonuniform mixtures. • have very large particles that settle out of solution. • can be filtered. • must be stirred to stay suspended. Examples include blood platelets, muddy water, and calamine lotion. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Solutions, Colloids, and Suspensions General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Solutions, Colloids, and Suspensions Properties of different types of mixtures: (a) suspensions settle out; (b) suspensions are separated by a filter; (c) solution particles go through a semipermeable membrane, but colloids and suspensions do not. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Study 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 _______. A. solution B. colloid C. suspension General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

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 ______. B. colloid General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Freezing Point Lowering, Boiling Point Elevation When a solute is added to water, the physical properties change and the • vapor pressure above the solution decreases. • boiling point of the solution increases. • freezing point of the solution decreases. These types of properties are called colligative properties; they depend only on the concentration of solute particles in the solution. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Vapor Pressure Lowering Increasing the concentration of solute particles in the solution • decreases the number of solvent particles at the surface of the solution. • prevents some of the solvent particles from leaving the solution. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Boiling Point Elevation Increasing the concentration of nonvolatile solute particles in the solution raises the boiling point of the solution, and • more solute particles in the solution lowers the vapor pressure. • the solution boils at a higher temperature than the normal boiling point. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Freezing Point Lowering Adding salt to an icy road when temperatures drop below freezing • allows the particles of salt to mix with the water. • lowers the freezing point of the ice. Adding ethylene glycol to water increases the number of hydrogen bonds that form in the solution, lowering the freezing point and raising the boiling point of the solution. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Particles in Solution A solute that is a nonelectrolyte dissolves as molecules, whereas a solute that is a strong electrolyte dissolves entirely as ions. • The solute in antifreeze, which is ethylene glycol, C 2 H 6 O 2, is a nonelectrolyte and dissolves as molecules in water. 1 mole C 2 H 6 O 2(l) = 1 mole C 2 H 6 O 2(aq) • The solute Na. Cl, a strong electrolyte, dissolves as ions in water. Na. Cl(s) Na+(aq) + Cl− (aq) 1 mole Na. Cl(s) = 1 mole Na+(aq) + 1 mole Cl− (aq) 1 mole Na. Cl(s) = 2 moles of particles in solution General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Particles in Solution The effect of solute particles on boiling points and freezing points is summarized below: General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Guide to Calculating Boiling Point Elevation, Freezing Point Lowering Core Chemistry Skill Calculating the Boiling Point/Freezing Point of a Solution General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Calculating Freezing Point Lowering In the northeastern United States during freezing temperatures, Ca. Cl 2 is spread on icy highways to melt the ice. Calculate the freezing point of a solution containing 0. 50 mole of Ca. Cl 2 in 1 kg of water. STEP 1 State the given and needed quantities. ANALYZE Given THE 0. 50 mole of Ca. Cl 2 PROBLEM 1 kg of water General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake Needed freezing point of solution © 2016 Pearson Education, Inc.

Calculating Freezing Point Lowering In the northeastern United States during freezing temperatures, Ca. Cl 2 is spread on icy highways to melt the ice. Calculate the freezing point of a solution containing 0. 50 mole of Ca. Cl 2 in 1 kg of water. STEP 2 Determine the number of moles of solute particles. Ca. Cl 2(s) Ca 2+(aq) + 2 Cl−(aq) 1 mole of Ca. Cl 2 = 3 moles of solute particles General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Calculating Freezing Point Lowering In the northeastern United States during freezing temperatures, Ca. Cl 2 is spread on icy highways to melt the ice. Calculate the freezing point of a solution containing 0. 50 mole of Ca. Cl 2 in 1 kg of water. STEP 3 Determine the temperature change using the moles of solute particles and the degrees Celsius change per mole of particles. × × General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Osmosis In osmosis, • water (solvent) flows from a lower to a higher solute concentration. • the level of the solution with the higher solute concentration rises. • the concentrations of the two solutions become equal with time. Water flows into the solution with a higher solute concentration until the flow of water becomes equal in both directions. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Osmotic Pressure Osmotic pressure is • equal to the pressure that would prevent the flow of additional water into the more concentrated solution. • greater as the number of dissolved particles in the solution increases. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Reverse Osmosis In a process called reverse osmosis, • a pressure greater than the osmotic pressure is applied to a solution, forcing it through a purification membrane. • the flow of water is reversed because water flows from an area of lower to higher water concentration, leaving behind the molecules and ions in solution. Reverse osmosis, used in desalination plants to obtain pure water from sea (salt) water, requires a large amount of energy. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Isotonic Solutions Because cell membranes in biological systems are semipermeable, osmosis is an ongoing process. The solutes in body solutions such as blood, tissue fluids, lymph, and plasma all exert osmotic pressure. Most IV solutions used in hospitals are isotonic solutions, which • exert the same osmotic pressure as body fluids such as red blood cells (RBCs). • include a 5. 0% (m/v) glucose or 0. 90% (m/v) Na. Cl isotonic solution. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Hypotonic and Hypertonic Solutions (a) In an isotonic solution, a red blood cell retains its normal volume. (b) Hemolysis: In a hypotonic solution, water flows into a red blood cell, causing it to swell and burst. (c) Crenation: In a hypertonic solution, water leaves the red blood cell, causing it to shrink. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Hypotonic Solution A hypotonic solution • has a lower solute concentration than red blood cells. • means water flows into cells by osmosis. The increase in fluid causes the cells to swell and burst, a condition called hemolysis. (b) Hemolysis: In a hypotonic solution, water flows into a red blood cell, causing it to swell and burst. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Hypertonic Solution A hypertonic solution • has a higher solute concentration than RBCs. • Involves water going out of the cells by osmosis. • causes crenation: RBCs shrink in size. (c) Crenation: In a hypertonic solution, water leaves the red blood cell, causing it to shrink. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

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). During dialysis, waste products and excess water are removed from the blood. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Study Check Indicate if each of the following solutions is A. isotonic. B. hypotonic. C. hypertonic. 1. ____ 2% Na. Cl solution 2. ____ 1% glucose solution 3. ____ 0. 5% Na. Cl solution 4. ____ 5% glucose solution General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Solution Indicate if each of the following solutions is A. isotonic. B. hypotonic. C. hypertonic. 1. _C__ 2% Na. Cl solution 2. _B__ 1% glucose solution 3. _B__ 0. 5% Na. Cl solution 4. _A__ 5% glucose solution General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Study Check When placed in each of the following, indicate if a red blood cell will A. not change. B. undergo hemolysis. C. undergo crenation. 1. ____ 5% glucose solution 2. ____ 1% glucose solution 3. ____ 0. 5% Na. Cl solution 4. ____ 2% Na. Cl solution General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Solution When placed in each of the following, indicate if a red blood cell will A. not change. B. undergo hemolysis. C. undergo crenation. 1. _A__ 5% glucose solution 2. _B__ 1% glucose solution 3. _B__ 0. 5% Na. Cl solution 4. _C__ 2% Na. Cl solution General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.

Concept Map Solutions General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.