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The Nature of Solutions Review Book Unit 7

The Nature of Solutions Review Book Unit 7. Solutions HW P 120 QUESTIONS 1 TO 12. DEFINITIONS – SOLUTION – SOLUTE – SOLVENT – HOMOGENEOUS MIXTURE CONCENTRATION – DILUTE VS CONCENTRATED THE NATURE OF SOLUTIONS SOLVATION. Some Definitions.

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The Nature of Solutions Review Book Unit 7

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  1. The Nature of SolutionsReview Book Unit 7 Solutions HW P 120 QUESTIONS 1 TO 12

  2. DEFINITIONS – SOLUTION – SOLUTE – SOLVENT – HOMOGENEOUS MIXTURE • CONCENTRATION – DILUTE VS CONCENTRATED • THE NATURE OF SOLUTIONS • SOLVATION

  3. Some Definitions A solution is a HOMOGENEOUS mixture of 2 or more substances in a single phase. One constituent is usually regarded as the SOLVENTand the others as SOLUTES.

  4. A. Definitions • Solution - homogeneous mixture Solute - substance being dissolved Solvent - present in greater amount

  5. Parts of a Solution • SOLUTE – the part of a solution that is being dissolved (usually the lesser amount). Uniformly spread in the solvent • SOLVENT – the part of a solution that dissolves the solute (usually the greater amount) • Solute + Solvent = Solution

  6. What happens when a solute dissolves in a solvent? • Solvation – the process of dissolving solute particles are surrounded by solvent particles First... solute particles are separated and pulled into solution Then...

  7. How Does a Solution Form? As a solution forms, the solvent pulls solute particles apart and surrounds, or solvates, them.

  8. CHARACTERISTICS OF A LIQUID SOLUTION • 1.- Homogeneous mixtures, particles are evenly spread. • 2.- Dissolved particles are too small to be seen, therefore solutions are clear and do not disperse light. • 3.- Can not be separated by filtration. Dissolved particles are too small and will pass trough any filter. • 4.- Stable. Dissolved particles will not come out of the solution and will not settle.

  9. Solutions Homogeneous mixtures. Solvation is the process by which the solution forms.

  10. April 7 • In your notebook answer the following question • Is air a solution? • Explain your reasoning

  11. Solutions are not always liquids • Solutions are homogeneous mixtures of two or more pure substances. • In a solution, the solute (present in smaller amount) is dispersed uniformly throughout the solvent (present in largest amount).

  12. SOLUBILITY • FACTORS THAT AFFECT SOLUBILITY • NATURE OF SUBSTANCES • TEMPERATURE • PRESSURE

  13. Solubility A measure of how much solute can be dissolved in an amount of solvent at a given temperature.

  14. A substance can be… • Soluble in a solvent. • Example: sugar is soluble in water. • Miscible is the term used when the two components are liquids and they dissolve in one another. • Example: alcohol and water are miscible • Insoluble in a solvent • Example: sand is insoluble in water. • Immiscible is the term used when the two components are liquids and they do not mix. • Example: oil and water are immiscible

  15. What affects Solubility? 1. Nature of Solute 2. Temperature 3. Pressure * graph

  16. Nature of Solute • A polar solute molecule (alcohol) dissolves in a polar solvent (water). • A nonpolar solute (oil paint) dissolves in a nonpolar solvent (turpentine) “Like Dissolves Like”

  17. Solubility for ionic compoundsTable F • This table is used to predict if a double replacement reaction will occur. If it the reaction produces an insoluble compound it occurs. If the products of the reaction are filtered the insoluble compound will remain in the filter paper

  18. Table F

  19. Pb(NO3)2 + 2KI  PbI2 + 2KNO3 • NaCl + AgNO3  AgCl + NaNO3 • CuSO4 + Na2CO 3  Na2SO4 + CuCO3

  20. Questions • Is NaCl soluble? Yes! • Is AgBr soluble? No!

  21. TABLE F SOLUBILITY GUIDELINES FOR AQ SOL ANSWERS • 4 • 1 • 3 • 4 • 3 • 4 • 4 • 3 • 4 • 10. 1 • 11. Hydroxide ion • B) NaOH • 12) a Yes • B) Ba(OH)2 or • Sr(OH)2 • 13 soluble

  22. When temperature increases… • Solubility of a gasdecreases • Solubility of a solidincreases

  23. Makes gas more soluble  ex. Soda can Has almost no effect on liquids and solids 3 Pressure • High pressure forces carbon dioxide into water to make soda. • - When you open the cap, there is less pressure on the soda b/c the soda fizzes and gas escapes.

  24. Gases are more soluble at • high pressures • EX: nitrogen narcosis, the “bends,” soda

  25. Solubility Curves • Solubility • maximum grams of solute that will dissolve in 100 g of solvent at a given temperature • varies with temp • based on a saturated solution

  26. C. Solubility • Solubility Curve • shows the dependence of solubility on temperature

  27. UNSATURATED SOLUTION more solute dissolves SATURATED SOLUTION no more solute dissolves SUPERSATURATED SOLUTION becomes unstable, crystals form C. Solubility concentration

  28. Definitions Solutions can be classified as saturated or unsaturated. A saturated solution contains the maximum quantity of solute that dissolves at that temperature. An unsaturated solution contains less than the maximum amount of solute that can dissolve at a particular temperature

  29. Supersaturated Sodium Acetate • One application of a supersaturated solution is the sodium acetate “heat pack.”

  30. C. Solubility • Solids are more soluble at... • high temperatures. • Gases are more soluble at... • low temperatures & • high pressures (Henry’s Law). • EX: nitrogen narcosis, the “bends,” soda

  31. Determining Electrical Conductivity • When a solution is soluble, it has ions that can conduct electricity (electrolytes) Ex. NaCl • When a solution is insoluble, it cannot conduct electricity (non-electrolytes or poor electrolytes) • Ex. AgBr

  32. Solubility curves worksheet answers • 1 KI • 2 KClO3 • 3 SO2 • 4 134 g • 5 SO2, NH3 and HCl • 6 Sol at 50 C 115 g at 10 C 80 g difference 35 g 7 ~ 47 C • 8 KNO3 and NaNO3 • 9 NaCl • 10 KNO3 • 11 ~ 57.5 g • 12 ~ 46 g • 13 38 C • 14 114g will precipitate • 15 60 g • 16 12 g

  33. Set 1 Solubility curves • 2 • 1 • 1(turn page around) • 2 • 4(turn page again) • 4 • 2 • 3 • 1 • 6 to 8 g • a- As P decreases, solubility decreases too. b- As T increases, solubility decreases 12 a KNO3

  34. Ways of expressing concentration • MOLARITY • % BY MASS, BY VOLUME • PPM

  35. CONCENTRATION The amount of solute in the solution. Relative terms • Diluted: Small amount of solute in relation to the amount of solvent • Concentrated: Large amount of solute in relation with the solvent.

  36. moles solute ( M ) = Molarity liters of solution Concentration of Solute The amount of solute in a solution is given by its concentration.

  37. Example • If you have 50 moles (mol) of solute (salt) in 25 liters (L) of solution and you want to know the molarity (concentration), look at Table T for the molarity formula. Molarity = moles of solute / liters of solution 50 moles / 25 liters = 2M

  38. 1.0 L of water was used to make 1.0 L of solution. Notice the water left over.

  39. Preparing Solutions • Weigh out a solid solute and dissolve in a given quantity of solvent. • Dilute a concentrated solution to give one that is less concentrated.

  40. PROBLEM: Dissolve 5.00 g of NiCl2•6 H2O in enough water to make 250 mL of solution. Calculate the Molarity. Step 1: Calculate moles of NiCl2•6H2O Step 2: Calculate Molarity [NiCl2•6 H2O] = 0.0841 M

  41. USING MOLARITY What mass of oxalic acid, H2C2O4, is required to make 250. mL of a 0.0500 M solution? Step 1: Change mL to L. 250 mL * 1L/1000mL = 0.250 L Step 2: Calculate. Moles = (0.0500 mol/L) (0.250 L) = 0.0125 moles Step 3: Convert moles to grams. (0.0125 mol)(90.00 g/mol) = 1.13 g moles = M•V

  42. Learning Check How many grams of NaOH are required to prepare 400. mL of 3.0 M NaOH solution? 1) 12 g 2) 48 g 3) 300 g

  43. Calculating Concentrations Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g of H2O. Calculate molality and % by mass of ethylene glycol.

  44. Try this molality problem • 25.0 g of NaCl is dissolved in 5000. mL of water. Find the molality (m) of the resulting solution. m = mol solute / kg solvent 25 g NaCl 1 mol NaCl 58.5 g NaCl = 0.427 mol NaCl Since the density of water is 1 g/mL, 5000 mL = 5000 g, which is 5 kg 0.427 mol NaCl 5 kg water = 0.0854 m salt water

  45. APRIL 25 • DO NOW – REVIEW MOLARITY • % BY MASS, % BY VOLUME, ppm • COLLIGATIVE PROPERTIES • HW SOLUTIONS TAKE HOME TEST!!!! • DUE MONDAY

  46. Two Other Concentration Units % by mass grams solute grams solution % by mass = X 100

  47. Two Other Concentration Units Ppm = parts per million grams solute grams solution X 1000,000 Ppm =

  48. Calculating Concentrations Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g of H2O. Calculate m & % of ethylene glycol (by mass). Calculate weight %

  49. Learning Check A solution contains 15 g Na2CO3 and 235 g of H2O? What is the mass % of the solution? 1) 15% Na2CO3 2) 6.4% Na2CO3 3) 6.0% Na2CO3

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