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MOLA L ITY – Ch 13, p. 416

Variables. Units. MOLA L ITY – Ch 13, p. 416. Quantifies the concentration of a solution. Molality ( m ) = mol solute = n = mol mass solvent m kg Read as “moles solute per kilogram solvent”. MOLALITY – Ch 13.

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MOLA L ITY – Ch 13, p. 416

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  1. Variables Units MOLALITY – Ch 13, p. 416 Quantifies the concentration of a solution. Molality (m) = mol solute = n = mol mass solvent m kg Read as “moles solute per kilogram solvent”

  2. MOLALITY – Ch 13 Example 1: “If 80.0 g sodium hydroxide, which is 2 mol, is dissolved in 1 kg water, a 2.00m solution of NaOH is produced.” p.416

  3. MOLALITY – Ch 13 Example 1: “If 80.0 g sodium hydroxide, which is 2 mol, is dissolved in 1 kg water, a 2.00m solution of NaOH is produced.” p.416 Why use molality? Its value does not change with temperature changes. As opposed to molarity M = mol L

  4. MOLALITY – Ch 13 Example 2: Determine the molal concentration of a solution containing 8.13 g ethylene glycol, HOCH2CH2OH, dissolved in 166 g water.

  5. Example 2: Determine the molal concentration of a solution containing 8.13 g ethylene glycol, HOCH2CH2OH, dissolved in 166 g water. Given:

  6. Example 2: Determine the molal concentration of a solution containing 8.13 g ethylene glycol, HOCH2CH2OH, dissolved in 166 g water. Given: mass solute = 8.13 g

  7. Example 2: Determine the molal concentration of a solution containing 8.13 g ethylene glycol, HOCH2CH2OH, dissolved in 166 g water. Given: mass solute = 8.13 g mass solvent = 166 g

  8. Example 2: Determine the molal concentration of a solution containing 8.13 g ethylene glycol, HOCH2CH2OH, dissolved in 166 g water. Given: mass solute = 8.13 g mass solvent = 166 g Unknown:

  9. Example 2: Determine the molal concentration of a solution containing 8.13 g ethylene glycol, HOCH2CH2OH, dissolved in 166 g water. Given: mass solute = 8.13 g mass solvent = 166 g Unknown: m

  10. Example 2: Determine the molal concentration of a solution containing 8.13 g ethylene glycol, HOCH2CH2OH, dissolved in 166 g water. Given: mass solute = 8.13 g mass solvent = 166 g Unknown:m Need:

  11. Example 2: Determine the molal concentration of a solution containing 8.13 g ethylene glycol, HOCH2CH2OH, dissolved in 166 g water. Given: mass solute = 8.13 g mass solvent = 166 g Unknown: m Need: molar mass ethylene glycol

  12. Example 2: Given: mass solute = 8.13 g mass solvent = 166 g Unknown: m Need: molar mass = 62.068 g ethylene glycol mol m = n m

  13. Example 2: Given: mass solute = 8.13 g mass solvent = 166 g Unknown: m Need: molar mass = 62.068 g mol m = n = 8.13 g m

  14. Example 2: Given: mass solute = 8.13 g mass solvent = 166 g Unknown: m Need: molar mass = 62.068 g mol m = n = 8.13 g mol m 62.068 g

  15. Example 2: Given: mass solute = 8.13 g mass solvent = 166 g Unknown: m Need: molar mass = 62.068 g mol m = n = 8.13 g mol m 62.068 g

  16. Example 2: Given: mass solute = 8.13 g mass solvent = 166 g = .166 kgUnknown: m Need: molar mass = 62.068 g mol m = n = 8.13 g mol m 62.068 g

  17. Example 2: Given: mass solute = 8.13 g mass solvent = 166 g = .166 kg Unknown: m Need: molar mass = 62.068 g mol m = n = 8.13 g mol m .166 kg H2O 62.068 g

  18. Example 2: Given: mass solute = 8.13 g mass solvent = 166 g = .166 kg Unknown: m Need: molar mass = 62.068 g mol m = n = 8.13 g mol .789 mol m .166 kg H2O 62.068 g kg

  19. Example 2: Given: mass solute = 8.13 g mass solvent = 166 g = .166 kg Unknown: m Need: molar mass = 62.068 g mol m = n = 8.13 g mol .789 m m .166 kg H2O 62.068 g

  20. Example 3: A solution of iodine, I2, in carbon tetrachloride, CCl4, is needed for a chemical test. How much iodine must be added to prepare a 0.480 m solution of iodine in CCl4 if 100.0 g of CCl4 is used?

  21. Example 3: A solution of iodine, I2, in carbon tetrachloride, CCl4, is needed for a chemical test. How much iodine must be added to prepare a 0.480 m solution of iodine in CCl4 if 100.0 g of CCl4 is used? Given:

  22. Example 3: A solution of iodine, I2, in carbon tetrachloride, CCl4, is needed for a chemical test. How much iodine must be added to prepare a 0.480 m solution of iodine in CCl4 if 100.0 g of CCl4 is used? Given: molality = 0.480 m

  23. Example 3: A solution of iodine, I2, in carbon tetrachloride, CCl4, is needed for a chemical test. How much iodine must be added to prepare a 0.480 m solution of iodine in CCl4 if 100.0 g of CCl4 is used? Given: molality = 0.480 m mass solvent = 100.0 g CCl4

  24. Example 3: A solution of iodine, I2, in carbon tetrachloride, CCl4, is needed for a chemical test. How much iodine must be added to prepare a 0.480 m solution of iodine in CCl4 if 100.0 g of CCl4 is used? Given: molality = 0.480 m mass solvent = 100.0 g CCl4 Unknown:

  25. Example 3: A solution of iodine, I2, in carbon tetrachloride, CCl4, is needed for a chemical test. How much iodine must be added to prepare a 0.480 m solution of iodine in CCl4 if 100.0 g of CCl4 is used? Given: molality = 0.480 m mass solvent = 100.0 g CCl4 Unknown: mass solute I2

  26. Example 3: A solution of iodine, I2, in carbon tetrachloride, CCl4, is needed for a chemical test. How much iodine must be added to prepare a 0.480 m solution of iodine in CCl4 if 100.0 g of CCl4 is used? Given: molality = 0.480 m mass solvent = 100.0 g CCl4 Unknown: mass solute I2 Need:

  27. Example 3: A solution of iodine, I2, in carbon tetrachloride, CCl4, is needed for a chemical test. How much iodine must be added to prepare a 0.480 m solution of iodine in CCl4 if 100.0 g of CCl4 is used? Given: molality = 0.480 m mass solvent = 100.0 g CCl4 Unknown: mass solute I2 Need: molar mass I2

  28. Example 3: Given: molality = 0.480 m mass solvent = 100.0 g CCl4 Unknown: mass solute I2 Need: molar mass I2 =

  29. Example 3: Given: molality = 0.480 m mass solvent = 100.0 g CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol

  30. Example 3: Given: molality = 0.480 m mass solvent = 100.0 g CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol m = n m

  31. Example 3: Given: molality = 0.480 m mass solvent = 100.0 g CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol m = n  n = m•m m

  32. Example 3: Given: molality = 0.480 m mass solvent = 100.0 g CCl4 = 0.1000 kg Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol m = n  n = m•m m

  33. Example 3: Given: molality = 0.480 m mass solvent = 0.1000 kg CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol n = m•m0.480 m

  34. Example 3: Given: molality = 0.480 m mass solvent = 0.1000 kg CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol n = m•m0.480 mol kg CCl4

  35. Example 3: Given: molality = 0.480 m mass solvent = 0.1000 kg CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol n = m•m0.480 mol0.1000 kg CCl4 kg CCl4

  36. Example 3: Given: molality = 0.480 m mass solvent = 0.1000 kg CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol n = m•m0.480 mol0.1000 kg CCl4 kg CCl4

  37. Example 3: Given: molality = 0.480 m mass solvent = 0.1000 kg CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol n = m•m0.480 mol0.1000 kg CCl4 .0480 mol I2 kg CCl4

  38. Example 3: Given: molality = 0.480 m mass solvent = 0.1000 kg CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol n = m•m0.480 mol0.1000 kg CCl4 .0480 mol I2 kg CCl4

  39. Example 3: Given: molality = 0.480 m mass solvent = 0.1000 kg CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol 0.0480 mol I2 253.808 g I2 mol I2

  40. Example 3: Given: molality = 0.480 m mass solvent = 0.1000 kg CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol 0.0480 mol I2 253.808 g I2 mol I2

  41. Example 3: Given: molality = 0.480 m mass solvent = 0.1000 kg CCl4 Unknown: mass solute I2 Need: molar mass I2 = 253.808 g/mol 0.0480 mol I2 253.808 g I2 12.2 g I2 mol I2

  42. Example 4: What is the molality of a solution containing 18.2 g HCl and 250. g water?

  43. Example 4: What is the molality of a solution containing 18.2 g HCl and 250. g water? 2.00 m

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