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Pen or Pencil Piece of paper TAKE NOTES ON PAGE 3 Take out:
What is a SOLUTION?
What is a SOLUTE?
Solute is a substance being dissolved. Hint: it is usually present in smaller amount SUGAR SOLUTE
What is a SOLVENT?
Solvent is the substance that dissolves the solute. Hint: it is usually present in the greater amount. WATER SOLVENT
+ = +(tea) SOLUTE + SOLVENT = SOLUTION (or)
Regents Question: 08/02 #7 Which mixture can be separated by using the equipment shown? (1) NaCl(aq) and SiO2(s) (2) NaCl(aq) and C6H12O6(aq) (3) CO2(aq) and NaCl(aq) (4) CO2(aq) and C6H12O6(aq) þ (aq) stands for aqueous which means dissolved in water. Dissolved particles are too small to be trapped by the filter.
Solubility: Maximum quantity of solute that can dissolve in an amount of solvent at a specified temperature Measured in grams(solute)/grams(solvent)
Rate of Solution: measure of how fast a substance dissolves Factors that the Rate of Solution
Size of Particles: (solid solute) As surface area rate of solution To increase surface area, crush large crystals Example: sugar granules vs. sugar cubes Factors that the Rate of Solution
Stirring: Makes solute come in contact with solvent • Amount of solute in solution: The less solute in solution the faster more will dissolve. Factors that the Rate of Solution
Temperature: For liquids/solids: As T Rate of Soln. For gases: As T Rate of Soln. Factors that Affect the Rate of Solution
Nature of solute and solvent: “Like dissolves like” polar solutes dissolve in polar solvents example: ionic solids in water non polar solutes in non polar solvents Factors that Affect Solubility
Temperature: For Ionic solids: as T solubility example: Jell-O in boiling water For gases: as T solubility example: warm soda goes flat Factors that Affect Solubility
Pressure: For solids/liquids: As P changes, solubility does not change For gases: as P solubility Effervescence: escape of gas from soln. Factors that Affect Solubility
Solubility is the maximum amount of solute that a solvent can hold at a given temperature. • An unsaturated solution is one in which the solvent can dissolve more solute • A saturated solution is one in which the solvent has as much solute as it can hold • A supersaturated solution is one in which there is more solute dissolved than a solvent can normally hold. • Make a supersaturated solution by cooling a saturated solution • Supersaturated solutions are unstable and will precipitate the excess solute when a seed crystal is added. Solubility of a nonvolatile solute depends on temperature.
Table G shows the solubility of some gases and solids at various temperatures when dissolved in 100 grams of water.
A solution which is on the line is saturated • A solution below the line is unsaturated • A solution above the line is supersaturated
Unsaturated – the test crystal dissolves Saturated – the test crystal settles to the bottom Supersaturated – a large amount of crystals precipitate from the solution Add a test crystal to see if a solution is unsaturated, saturated or supersaturated.
Regents Question: 06/02 #40 According to Reference Table G, which solution is saturated at 30°C? (1) 12 grams of KClO3 in 100 grams of water (2) 12 grams of KClO3 in 200 grams of water (3) 30 grams of NaCl in 100 grams of water (4) 30 grams of NaCl in 200 grams of water þ
Regents Question: 08/02 #48 One hundred grams of water is saturated with NH4Cl at 50°C. According to Table G, if the temperature is lowered to 10°C, what is the total amount of NH4Cl that will precipitate? (1) 5.0 g (3) 30. g (2) 17 g (4) 50. g þ
Regents Question: 01/03 #65-66 When cola, a type of soda pop, is manufactured, CO2 (g) is dissolved in it. A capped bottle of cola contains CO2 (g) under high pressure. When the cap is removed, how does pressure affect the solubility of the dissolved CO2 (g)? A glass of cold cola is left to stand 5 minutes at room temperature. How does temperature affect the solubility of the CO2 (g)? As the pressure decreases, the solubility decreases. As the temperature increases, the solubility decreases.
Regents Question: 06/03 #42 Hexane (C 6 H 14 ) and water do not form a solution. Which statement explains this phenomenon? (1) Hexane is polar and water is nonpolar. (2) Hexane is ionic and water is polar. (3) Hexane is nonpolar and water is polar. (4) Hexane is nonpolar and water is ionic. þ
Soluble will dissolve Insoluble will not dissolve Page 21 top
Not all substances are soluble in water Reference Table F lists solubility rules and exceptions to those rules. Solubility Guidelines
Regents Question: 08/02 #40 Which of the following compounds is least soluble in water? (1) copper (II) chloride (2) aluminum acetate (3) iron (III) hydroxide (4) potassium sulfate þ
Regents Question: 06/03 #14 • According to Table F, which of these salts is least soluble in water? • LiCl • (2) RbCl • (3) FeCl2 • (4) PbCl2 þ
Concentration of Solution • The concentration of a solution is a measurement of the amount of solute dissolved in solution. • Dilute is very little solute • Concentrated is at or near saturation • Molarity is a [concentration] of moles/liter • Table T
Moles Molarity = Liters Regents Question: 06/02 #42 What is the molarity of a solution that contains 0.50 mole of NaOH in 0.50 liter of solution? (1) 1.0 M (3) 0.25 M (2) 2.0 M (4) 0.50 M þ
Regents Question: 08/02 #36 How many moles of solute are contained in 200 milliliters of a 1 M solution? (1) 1 (3) 0.8 (2) 0.2 (4) 200 þ
Molarity = moles liters Na 1 x 23.0 = 23.0 I 1 x 126.9 = 126.9 149.9 g / mole 0.010M = x 1.0 L Regents Question: 08/02 #49 What is the total number of grams of NaI(s) needed to make 1.0 liter of a 0.010 M solution? (1) 0.015 (3) 1.5 (2) 0.15 (4) 15 þ X = 0.010 moles 0.010 moles x 149.9 g/mole =
Parts Per Million • Parts per million ppm is often used to measure concentrations of solutes that are present in very small amounts Mass of Solute Mass of Solution X 1,000,000 Parts Per Million =