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SOLUTIONS

SOLUTIONS. Chapter 12. West Valley High School General Chemistry Mr. Mata. Standard 5. Students know that temperature, pressure, and surface area affect the dissolving process. Essential Question:. What are the components of a solution and how do solutions, suspensions, and colloids

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SOLUTIONS

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  1. SOLUTIONS Chapter 12 West Valley High School General Chemistry Mr. Mata

  2. Standard 5 • Students know that temperature, pressure, and surface area affect the dissolving process.

  3. Essential Question: What are the components of a solution and how do solutions, suspensions, and colloids differ from one another?

  4. What is a Solution? • Solution = homogeneous mixture of two or more substances. (solute & solvent) • Solute = substance being dissolved. • Solvent = substance doing the dissolving. • Homogeneous mixture = completely dissolved & uniform solute in solvent • Aqueous solution = solution in which the solvent is water.

  5. Parts of a Solution

  6. Homogeneous vs. Heterogeneous • 24-karat gold is pure gold = homogeneous • 14-karat gold is an alloy (mixture) Au, Ag, Cu = heterogeneous • 14-karat gold is 14/24 (58.3%) gold

  7. Solubility Terminology • Soluble = substance that can be dissolved. • Insoluble = substance that cannot be dissolved. • Solubility = measure of how much solute will dissolve in solvent. • Miscible = two liquids that dissolve in each other (ex: water & ethanol). • Immiscible = two liquids that don’t dissolve in each other (ex: H2O & oil).

  8. Immiscible Liquids

  9. Solubility Terminology • SATURATED—contains the maximum amount of solute. • UNSATURATED—contains less solute than a saturated solution. • SUPERSATURATED—contains more solute than it should.

  10. Solution Saturations

  11. Factors affecting Solubility • Stirring (agitation) increases solubility. • Surface Area (particle size) smaller size increases surface area: increases sol. • Pressure (gases) increased pressure increases gas solubility. • Temperature (solids & gases). solids: temp increase = increases solubility gases: temp increase = decrease solubility

  12. Solution Concentration • Concentration: measure of the amount of solute that is dissolved in a given quantity of solvent. • Dilute solution = solution that contains small amount of solute. • Concentrated solution = solution that contains a large amount of solute. • Molarity (M) = moles of solute/L of soln • Units = M or moles/Liter (mol/L).

  13. Suspensions • Suspension – particles in a solvent are so large that they settle to bottom unless agitated. • Ex: muddy water • Soil particles will sink to bottom. • Can be separated from heterogeneous mixtures by filtering.

  14. Colloids • Particles are intermediate in size between those in solutions and suspensions. • 1 nanometer (nm) to 1000 nm. • Cause mixture to look “cloudy”. • Ex: mayonnaise • Egg yolk keeps the oil droplets dispersed.

  15. MOLARITY Molarity (M) = moles of solute Liters of solution Units in mol/L or M

  16. Calculate the molarity of 0.8 mol of NaCl dissolved in 4 L of solution. M = moles solute Liters of solution M = 0.8 mol 4 L 0.2 mol/L or 0.2 M

  17. A saline solution contains 0.90 g NaCl in exactly 100 mL of solution. What is the molarity of the solution? M = moles solute Liters of solution 0.90 g NaCl x 1 mol NaCl = 0.02 mol NaCl 58 g NaCl 100 mL x 1 L = 0.1 L 1000 mL M = 0.02 mol = 0.2 mol/L or 0.2 M 0.1 L

  18. A solution contains 325 g CaCl2 in exactly 2500 mL of solution. What is the molarity of the solution? M = moles solute Liters of solution 325 g CaCl2 x 1 mol CaCl2 = 2.95 mol CaCl2 110 g CaCl2 2500 mL x 1 L = 2.5 L 1000 mL M = 2.95 mol = 1.2 mol/L or 1.2 M 2.5 L

  19. How many moles of solute are present in 1.5 L of 0.24 M Na2SO4? M = mol -> mol = ML L 0.24 M Na2SO4 = 0.24 mol/L Na2SO4 Mol = (0.24 mol/L) (1.5L) = 0.36 mol

  20. How many moles of solute are present in 20 L of 12 M H2SO4? M = mol -> mol = ML L 12 M H2SO4 = 12 mol/L H2SO4 Mol = (12 mol/L) (20L) = 240 mol

  21. Percent Solutions What is the percent by volume of ethanol in the final solution when 85 mL of ethanol is diluted with 250 mL of water? %v/v = volume of solute x 100 solution volume %v/v = 85 mL ethanol x 100 = 250 mL H2O = 34% ethanol (v/v)

  22. Percent Solutions What is the percent by volume of ethanol in the final solution when 300 mL of ethanol is diluted with 600 mL of water? %v/v = volume of solute x 100 solution volume %v/v = 300 mL ethanol x 100 = 600 mL H2O = 50% ethanol (v/v)

  23. Parts per Million • Parts per million (ppm) • Aqueous solutions: 1 ppm = 1000 ng/L The federal limit of lead in tap water is 0.015 ppm. Express this concentration in ng/L. 0.015 ppm x 1000 ng/L = 15 ng/L 1 ppm

  24. Parts per Million The federal limit of mercury in tap water is 0.0002 ppm. Express this concentration in ng/L. 0.0002 ppm x 1000 ng/L = .2 ng/L 1 ppm

  25. Chapter 12 SUTW Prompt • Describe the differences between an unsaturated, saturated, and supersaturated solution. • Complete a 10 -12 sentence paragraph using the SUTW paragraph format. Hilight using green, yellow, and pink. • Due Date: Tomorrow (start of class).

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