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Molarity & Solutions

Molarity & Solutions. Prescription drugs in the correct concentration make you better. In higher concentration they can kill you. Chemists need to make solutions that have precise concentrations. Pesticides must be in proper concentrations. Food additives must be in correct concentrations.

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Molarity & Solutions

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  1. Molarity & Solutions

  2. Prescription drugs in the correct concentration make you better. In higher concentration they can kill you.

  3. Chemists need to make solutions that have precise concentrations

  4. Pesticides must be in proper concentrations. Food additives must be in correct concentrations. A driver is legally impaired at 0.08 mg/mL blood alcohol content. Chemists control the concentration of chemicals using the concepts we will develop in this unit.

  5. Concentration • Concentration-the amount of solute that is dissolved into a solvent • Concentrated-when a solution has a high concentration of solute • Dilute-when a solution has a low concentration of solute

  6. Concentration… • Concentration can be described in terms of “weak” or “strong”, “concentrated” or “dilute”, but these are both relative terms and can be subjective.

  7. Molarity • Molarity is one way to measure concentration; it is the number of moles of solute per liter of solution. • The unit of molarity is mol/L, which can be abbreviated with an uppercase M.

  8. The concentrationof a solution tells you how much solute that is dissolved in a given amount of solvent (water). The molarity is the concentration of a solution. Molarity = Moles Liter 1. 2.255 moles of NaCl is dissolved in 4.0 L of water, calculate the molarity. Molarity =

  9. The concentration of a solution tells you how much solute that is dissolved in a given amount of solute (water). The molarity is the concentration of a solution. Molarity = Moles Liter 1. 2.255 moles of NaCl is dissolved in 4.0 L of water, calculate the molarity. Molarity = 2.255 moles 4.0 L

  10. The concentration of a solution tells you how much solute that is dissolved in a given amount of solute (water). The molarity is the concentration of a solution. Molarity = Moles Liter 1. 2.255 moles of NaCl is dissolved in 4.0 L of water, calculate the molarity. Molarity = 2.255 moles = 0.56 moles = 0.56 M(Molar) 4.0 L Liter

  11. 2. 5.00 g KOH is dissolved in 250. mL of water, calculate the molarity. Molarity =

  12. 2. 5.00 g KOH is dissolved in 250. mL of water, calculate the molarity. Molarity = 5.00 g 1

  13. 5.00 g KOH is dissolved in 250. mL of water, calculate the molarity. • K = 39.0 (mass off periodic table) • O = 16.0 • H = 1.0 • 56.0 g/mol • Molarity = 5.00 g x 1 mole • 1 56.0 g

  14. 5.00 g KOH is dissolved in 250. mL of water, calculate the molarity. • K = 39.0 (mass off periodic table) • O = 16.0 • H = 1.0 • 56.0 g/mol • Molarity = 5.00 g x 1 mole • 1 56.0 g • 0.250 L

  15. 5.00 g KOH is dissolved in 250. mL of water, calculate the molarity. • K = 39.0 (mass off periodic table) • O = 16.0 • H = 1.0 • 56.0 g/mol • Molarity = 5.00 g x 1 mole • 1 56.0 g • 0.250 L • = 0.356 M

  16. 3. How many moles are there in 205. mL of a 0.172 M solution?

  17. 3. How many moles are there in 205. mL of a 0.172 M solution? 0.172 moles 1 L

  18. 3. How many moles are there in 205. mL of a 0.172 M solution? 0.172 moles x 0.205 L 1 L 1

  19. 3. How many moles are there in 205. mL of a 0.172 M solution? 0.172 moles x 0.205 L = 0.0353 moles 1 L 1

  20. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution?

  21. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution? 0.250 L 1

  22. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution? 0.250 L x 0.500 moles 1 1 L

  23. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution? 0.250 L x 0.500 moles x 58.5 g 1 1 L 1 mole

  24. 4. How many grams NaCl are there in 250.0 mL of 0.500 M solution? 0.250 L x 0.500 moles x 58.5 g = 7.31 g 1 1 L 1 mole

  25. 5. How many grams of NaCl must be used to prepare a 100.0 mL of 0.250 M solution.

  26. 5. How many grams of NaCl must be used to prepare a 100.0 mL of 0.250 M solution. 0.1000 L 1

  27. 5. How many grams of NaCl must be used to prepare a 100.0 mL of 0.250 M solution. 0.1000 L x 0.250 moles 1 1 L

  28. 5. How many grams of NaCl must be used to prepare a 100.0 mL of 0.250 M solution. 0.1000 L x 0.250 moles x 58.5 g 1 1 L 1 mole

  29. 5. How many grams of NaCl must be used to prepare a 100.0 mL of 0.250 M solution. 0.1000 L x 0.250 moles x 58.5 g = 1.46 g 1 1 L 1 mole

  30. 6. How many milliliters of a 0.200 M solution of CoCl2 will contain 25.0 g?

  31. 6. How many milliliters of a 0.200 M solution of CoCl2 will contain 25.0 g? 25.0 g 1

  32. 6. How many milliliters of a 0.200 M solution of CoCl2 will contain 25.0 g? 25.0 g x 1 mole 1 129.9 g

  33. 6. How many milliliters of a 0.200 M solution of CoCl2 will contain 25.0 g? 25.0 g x 1 mole x 1 L 1 129.9 g 0.200 mol

  34. 6. How many milliliters of a 0.200 M solution of CoCl2 will contain 25.0 g? 25.0 g x 1 mole x 1 L x 1000 mL 1 129.9 g 0.200 mol 1 L

  35. 6. How many milliliters of a 0.200 M solution of CoCl2 will contain 25.0 g? 25.0 g x 1 mole x 1 L x 1000 mL = 962 mL 1 129.9 g 0.200 mol 1 L

  36. 7. Describe how you would prepare 100.0 mL of a 0.200 M solution of CoCl2. 0.1000 L x 0.200 moles x 129.9 g = 2.60 g 1 L 1 mole Weigh 2.60 g of CoCl2 Dissolve in water Transfer to a 100 mL volumetric flask and fill to the line

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