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Mixtures and Solutions

Reviewing Vocabulary In your textbook, read about the basic concepts of the three gas laws.

Match the definition in Column A with the term in Column B.

Column A Column B

__________ 1. The diffusion of solvent particles across a semipermeable membrane fromareas of lower solute concentration to areas of higher solute concentration

__________ 2. A mixture with particles that settle out if undisturbed

__________ 3. The erratic movement of colloid particles

__________ 4. The amount of additional pressure caused by water molecules moving into a solution

__________ 5. A measure of how much solute is dissolved in a specific amount of solvent or solution

__________ 6. The overall energy change that occurs when a solution forms

__________ 7. A heterogeneous mixture of intermediate–sized particles

__________ 8. The process of surrounding solute particles with solvent particles to form a solution

__________ 9. The ratio of the number of moles of solute in solution to the total number of moles of solute and solvent

__________ 10. The scattering of light by dispersed colloid particles

__________ 11. The statement that the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid

a. Brownian motion

b. colloid

c. concentration

d. heat of solution

e. Henry’s law

f. mole fraction

g. osmosis

h. osmotic pressure

i. solvation

j. Tyndall effect

k. suspension

Describe each pair of related terms.

12. soluble, insoluble_______________________________________________________________________________________________

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13. miscible, immiscible______________________________________________________________________________________________

14. molarity, molality______________________________________________________________________________________________

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Chemistry: Matter and Change Chapter Assessment1

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Understanding Main Ideas (Part A)

In the space at the left, write true if the statement is true; if the statement is false, change the italicized word or phrase to make it true.

__________ 1. A solution may exist as a gas, a liquid, or a solid depending on the state of the solvent.

__________ 2. Molar solutions are calculated and expressed in grams per liter.

__________ 3. The most common solvent among liquid solutions is ethanol.

__________ 4. Nonpolar solutes are more soluble in nonpolar solvents.

__________ 5. A supersaturated solution contains less dissolved solute than a saturated solution at the same temperature.

__________ 6. The lowering of the vapor pressure of a pure solvent when a solution is formed is a colligative property.

__________ 7. A 1M solution of a nonelectrolyte will have a lesser effect on the colligative properties of its solution than a 1M solution of an electrolyte will have on the colligative properties of its solution.

__________ 8. In an aerosol, the dispersing medium is a liquid.

__________ 9. A dilute solution contains a small amount of solute relative to the solute’s solubility.

__________ 10. Attractions between the dispersed particles and the particles of the dispersing medium of a colloid produce magnetic layers that keep the dispersed particles from settling out.

__________ 11. Boiling point depression is the temperature difference between a solution’s and a pure solvent’s boiling point.

Circle the letter of the response that best answers the question.

12. What term describes a solution in which the dissolved solute is in equilibrium with the undissolved solute?a. dilute solution b. saturated solution c. supersaturated solution d. unsaturated solution

13. Which of the following statements explains the solubility of ionic substances in water?a. The molar mass of water is 18.02 g/mol.b. An oxygen atom has six electrons in its outermost energy level.c. Water molecules are polar.d. Water is a covalent substance.

14. Which of the following compounds provides the most solute particles when completely dissociated in water?a. MgCl2 b. KBr c. NaCl d. Na3PO4

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Understanding Main Ideas (Part B)

Answer the following questions.

1. Briefly describe the solvation of sodium chloride to form an aqueous solution.______________________________________________________________________________________________

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2. How would you prepare each of the following solutions? Show your calculations.

a. 1.00 L of a 2.00M aqueous solution of sodium hydroxide (NaOH)

b. 90.0 mL of a 1.20M aqueous solution of sodium oxalate (Na2C2O4) from a 2.00M solution of Na2C2O4

3. What is the mole fraction of the solute in a 1.00m solution of barium chloride (BaCl2)? Show your calculations.

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Thinking CriticallyThe graph below shows the solubility versus temperature for two compounds, A and B. Use the graph to answer the questions below.

1. One of the curves represents carbon dioxide (CO2); the other represents tin(II) iodide (SnI2). Identify compounds A and B. Explain your reasoning.______________________________________________________________________________________________

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2. A third substance, HgBr2, has a solubility of 0.50 g HgBr2/100.0 g H2O at 20°C. If the solution is saturated at this temperature, calculate the molality of the solution.

3. Calculate the molarity of the HgBr2 solution. Assume the density of the solution is the same as the density of the solvent.

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Applying Scientific MethodsA time-release capsule releases a drug at a constant rate so that the concentration of the drug in the body is not so high as to damage the body nor so low as to be ineffective. The diagram below shows such a capsule.

Notice that the capsule has two compartments separated by an impermeable, elastic membrane. One compartment contains the drug, the other a saturated solution of sodium chloride. The outer wall of the drug compartment consists of a rigid, selectively permeable material. The wall is designed to allow only molecules of the drug to pass outward through the wall. The outer wall of the compartment containing the sodium chloride solution consists of a semipermeable membrane. A thin, protective coating that dissolves when the capsule enters the body covers the entire capsule.

The graph shows the concentration of the sodium chloride solution in the capsule over time after the capsule has entered the body.

Use the diagram of the capsule and the graph to answer questions 1 and 2.

1. What happens to the concentration of the aqueous sodium chloride solution over time?______________________________________________________________________________________________

2. What process would account for your answer to question 1? Explain.______________________________________________________________________________________________

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Chemistry: Matter and Change Chapter Assessment5

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Applying Scientific Methods, continued

3. The graph below shows the volume of the aqueous sodium chloride solution in the capsule after the capsule has entered the body. Explain whether the graph supports your answer to question 2.

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4. Which of the following graphs represents the mass of the drug in the capsule after the capsule has entered the body? Explain your choice.

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5. What are two functions of the elastic, impermeable membrane separating the aqueous sodium chloride solution and the drug? How is each function related to a property of the membrane?______________________________________________________________________________________________

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Chemistry: Matter and Change Chapter Assessment6

TEACHER GUIDE AND ANSWERS

Chapter Assessment - Chapter 14 – Mixtures and Solutions

Reviewing Vocabulary1. g2. k3. a4. h5. c6. d7. b8. i9. f

10. j11. e12. If a substance dissolves in another substance, the first

substance is soluble. If a substance does not dissolve in another substance, the first substance is insoluble.

13. Miscible liquids are soluble in each other, and immiscible liquids are not.

14. Molarity is the number of moles of solute dissolved per liter of solution. Molality is the ratio of the number of moles of solute dissolved in one kilogram of solvent.

Understanding Main Ideas (Part A)1. true2. moles per liter3. water4. true5. more6. true7. true8. gas9. true

10. electrostatic11. boiling point elevation12. b13. c14. d

Understanding Main Ideas (Part B)1. When a sodium chloride crystal is placed in water, the

charged ends of the polar water molecules attract the positive sodium ions and the negative chloride ions. Because the attraction between the water molecules and the ions is greater than the attraction between the ions in the crystal, the ions break away from the crystal. The water molecules surround the ions and keep them separated, forming a solution.

2. a. Molarity moles of solute/liters of solution 2.00M NaOH 2.00 mol NaOH/1.00 L of solution(2.00 )(40.00 g NaOH/1 ) 80.00 g NaOHAdd 80.00 g of NaOH to a 1-L volumetric flask. Add distilled water to the flask to completely dissolve the NaOH. Carefully add additional distilled water to bring the solution up to the 1-L calibration line.b. M1V1 M2V2

V1 V2(M2/M1) (90.0 mL)(1.20 /2.00 ) 54.0 mLAdd 54.0 mL 2.00M Na2C2O4 to a graduated cylinder. Carefully add distilled water to bring the solution up to the 90.0-mL calibration line.

3. Molality moles of solute/kilograms of solvent 1.00m BaCl2 1.00 mol BaCl2/1.00 kg H2O

(1.00 103 )(1 mol H2O/18.02 ) 55.5 mol H2O

/( ) 1.00 mol BaCl2/(1.00 mol BaCl2 55.5 mol H2O)

0.0177

Thinking Critically1. Compound A is tin(II) iodide, and compound B is

carbon dioxide. The curve for compound A indicates that the solubility of the substance increases with increasing temperature. This trend is characteristic of most solid solutes dissolved in liquid solvents, such as tin(II) iodide dissolved in water. The curve for compound B indicates that the solubility of the substance decreases with increasing temperature. This trend is characteristic of gases dissolved in liquid solvents, such as carbon dioxide dissolved in water.

Chemistry: Matter and Change Teacher Guide and Answers7

TEACHER GUIDE AND ANSWERS

2. (0.50 )(1 mol HgBr2/360.30 ) 1.4103 mol HgBr2

(100.0 g H2O)(1 kg/1000 g) 0.1000 kg H2OMolality moles of solute/kilograms of solvent 1.4103 mol HgBr2/0.1000 kg H2O 1.4102 mol HgBr2/kg H2O 1.4102 m HgBr2

3. Mass of solution 1000 g 0.50 g 1000.50 gVolume of solution (1000.50 g)(1 kg/1000 g) (1 L/1 kg) 0.1005 LMolarity moles of solute/liters of solution 1.410-3 mol HgBr2/0.1005 L 1.4102 mol HgBr2/L 1.4102 M HgBr2

Applying Scientific Methods1. The solution becomes dilute.2. Osmosis; water diffuses through the semipermeable

membrane from the body, which has a lower concentration of sodium chloride, to the capsule, which has a higher concentration of sodium chloride.

3. Yes, the graph supports the explanation because the graph shows that the volume of the sodium chloride solution increases. The increased volume means that water is diffusing into the compartment through the semipermeable membrane.

4. Graph c; ifthe drug is entering the body at a constant rate, it must be leaving the capsule at a constant rate. So, as time passes, the mass of the drug inside the capsule must decrease at a constant rate.

5. Because the membrane is impermeable, it keeps water from diffusing through the membrane into the drug and diluting it. Because the membrane is elastic, it allows the volume of the sodium chloride to expand into the drug compartment and push the drug through the capsule wall into the body.

Chemistry: Matter and Change Teacher Guide and Answers8