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Reading: Chapter 16 sections 4-end HW 15: 7/16/14

Reading: Chapter 16 sections 4-end HW 15: 7/16/14 Chap . 15 #s 14, 15, 17, 21, 23, 25, 28, 30, 35, 40, 41, 45, 49, 55, 59, 63-73 odd, 91, 94, 105, 118, 122, 126, 127, 129 Lab Tomorrow (WET lab!) Exam 3 Tomor. Rate of Dissolving.

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Reading: Chapter 16 sections 4-end HW 15: 7/16/14

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  1. Reading: Chapter 16 sections 4-end • HW 15: 7/16/14 • Chap. 15 #s 14, 15, 17, 21, 23, 25, 28, 30, 35, 40, 41, 45, 49, 55, 59, 63-73 odd, 91, 94, 105, 118, 122, 126, 127, 129 • Lab Tomorrow (WET lab!) • Exam 3 Tomor

  2. Rate of Dissolving • There are three ways we can speed up the rate of dissolving for a solid compound: • Heating the solution: • This increases the kinetic energy of the solvent, and the solute is attacked faster by the solvent molecules. • Stirring the solution: • This increases the interaction between solvent and solute molecules. • Grinding the solid solute: • There is more surface area for the solvent to attack.

  3. Saturated Solutions • A solution containing exactly the maximum amount of solute at a given temperature is a saturated solution. • A solution that contains less than the maximum amount of solute is an unsaturated solution.

  4. Saturated Solutions • Under certain conditions, it is possible to exceed the maximum solubility of a compound. A solution with greater than the maximum amount of solute is a supersaturated solution.

  5. Supersaturation

  6. Concentration of Solutions • The concentration of a solution tells us how much solute is dissolved in a given quantity of solution. • There are several measurements for the concentration of a solution: • mass/mass percent • mass/volume percent • volume/volume percent • molarity • ppm (parts-per-million) • osmolarity

  7. mass of solute mass solute × 100% = m/m % mass of solution × 100% = m/m % mass solute + mass solvent Concentration – Mass Percent • Mass percent concentration compares the mass of solute to the mass of solvent.

  8. mass of solute × 100% = m/v % volof solution Concentration – m/v Percent • Mass/volume percent concentration compares the mass of solute to the volume of solution.

  9. volof solute volsolute × 100% = v/v % volof solution × 100% = v/v % volsolute + volsolvent Concentration – Volume Percent • Percent by volume concentration compares the volume of solute to the volume of solvent.

  10. 5.00 g NaCl × 100% = m/m % 5.00 g NaCl + 97.0 g H2O 5.00 g NaCl × 100% = 4.90 % 102 g solution Concentration – Mass Percent • A student prepares a solution from 5.00 g NaCl dissolved in 97.0 g of water. What is the concentration in m/m %?

  11. Concentration – Mass Percent What is the mass percent of a solution that is made up of 75.0 grams of lithium fluoride and 125 grams of water?  solute given: 75.0 g LiF  solvent 125 g water asked: mass % of the solution

  12. Concentration – Mass Percent What is the mass percent of a solution which weighs 625 grams and contains 100.0 grams of potassium bromide?  solution given: 625 g solution  solute 100.0 g KBr asked: mass % of the solution

  13. Concentration – Volume Percent What is the volume percent of a solution which contains 30.0 mL ethanol and 720.0 mL of water?  solvent given: 720.0 mL water  solute 30.0 mL ethanol asked: volume % of the solution

  14. Solutions Solution – A system in which one or more substances are mixed or dissolved in another substance. When water is the solvent, write as (aq). NaCl(aq) for example. The (aq) means MIXED with water!!! Solute – The substance that is being dissolved, or the least abundant component, of a solution. Each solute is a pure substance

  15. ________ Percent Unit Factors • We can write several unit factors based on the concentration 4.00% by volume (v/v) ethanol:

  16. ________ Percent Unit Factors • We can write several unit factors based on the concentration 8.11% by mass (m/m) ethanol:

  17. Concentration – Molarity A 0.125 M solution of sodium chloride bad ADVICE! Cross out the M and write A 0.125 solution of sodium chloride better BEST!!! When given to you, molarity is ALWAYS per 1 L

  18. Avogadro’s # The mole Only 3 options of what to do with the mole: mole particles molar mass mole mass molar volume mole volume mole-to-mole ratio mole “X” mole “Y” molarity L solution mole solute

  19. Molarity Unit Factors We can write 2 conversion factors based on the concentration 6.00 MNaOH:

  20. Concentration – Molarity How many moles of NaClare in 2.5 L of a 0.355 M solution of sodium chloride?

  21. Concentration – Molarity What volume of a 1.250 M potassium hypoiodite solution will contain 0.00456 moles of potassium hypoiodite?

  22. Concentration – Molarity How many grams of Li2CrO4are in 250.0 mL of 0.100 MLi2CrO4solution? = 3.25 g Li2CrO4

  23. Concentration – Molarity • What volume of 12.0 M HCl contains 9.15 g of HCl solute (36.46 g/mol)? • We want volume; we have grams HCl. = 20.9 mL HCl solution

  24. Concentration – Molarity How would you make 0.0250 L of a 0.0998 M solution of rubidium carbonate (230.95 g/mol)? = 0.576 g Rb2CO3 Add 0.576 grams of rubidium carbonate to 0.0250 L (25.0 mL) of water.

  25. (0.10 M) × (5.00 L) V1 = = 0.083 L 6.0 M Dilution Problem • What volume of 6.0 M NaOH needs to be diluted to prepare 5.00 L if 0.10 M NaOH? • We want final volume and we have our final volume and concentration. M1 × V1 = M2 × V2 (6.0 M) × V1 = (0.10 M) × (5.00 L)

  26. Solution Stoichiometry Problem What is the mass of all products and reactants after the following reaction finishes: 37.5 mL of 0.100 M aluminum bromide solution reacts with 80.1 mL of 0.133 M silver nitrate solution? THIS IS HOMEWORK. IT IS DUE NEXT CLASS!

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