1 / 63

Solutions Part II

Solutions Part II. DHS Chemistry Chapter 15. I. Concentrations of Solutions. The concentration of a solution is a measure of the amount of solute that is dissolved in a given quantity of solvent. Amount of solute vs. amount of water. Dilute vs Concentrated.

drea
Download Presentation

Solutions Part II

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Solutions Part II DHS Chemistry Chapter 15

  2. I. Concentrations of Solutions • The concentration of a solution is a measure of the amount of solute that is dissolved in a given quantity of solvent. Amount of solute vs. amount of water

  3. Dilute vs Concentrated Little solute a lot of solute

  4. Very Concentrated

  5. Less Concentrated

  6. Concentrated solutions • A concentrated solution is one that contains a high concentration of solute.

  7. Dilute solutions • A dilute solution contains a small concentration of solute.

  8. Pictorial Representation

  9. Pictorial Representation

  10. There are several ways to express concentration. These include: percent solutions (by volume or mass), molarity, or molality.

  11. A. Percent Solutions

  12. Percent Solutions • % solute = amount of solute _ • 100 TOTAL amount of solvent • solution • 3 types: • (%m/m) same units • (%v/v) same units • (%m/v) needs to be g/mL

  13. How much vinegar is just acetic acid? 5% of vinegar is acetic acid

  14. Percent by Volume % by volume (% (v/v)) = volume of solute 100 Volume of solution units must be the same (solute + solvent) Tip: watch out for the wording. You may need to add the volume of the solute and solvent to get the volume of the total solution

  15. Percent by Mass % by mass (% (m/m)) = mass of solute 100 mass of solution *units must be the same (solute + solvent) Tip: watch out for the wording. You may need to add the mass of the solute and solvent to get the volume of the total solution

  16. Percent Mass by Volume % mass by volume (% (m/v) = mass of solute (g) 100 volume of solution (mL) *units must g/mL

  17. Ex 1: 20 mL of alcohol is diluted with water to a total volume of 65 mL. What is the percentage of alcohol, by volume? %(v/v) =Volume of solute 100 Volume of solution %(v/v)= ? % = 20 mL alcohol 30.8% Alcohol by volume 100 65 mL H2O

  18. 65 mL alcohol + water 20 mLalcohol 30.8% of this solution is alcohol. The rest is water.

  19. Ex 2 : A solution containing 7 g of NaCl in 165 g of solution. What is the percent of NaCl by mass? 158 g of solvent (water) ? %NaCl (m/m)= 4.24% 7 g NaCl 100 165 g solution Solution = Solute + solvent Solution = 7 g + 158 g

  20. Children’s Dose vs Adult Dose Diphenhydramine hydrochloride (active ingredient in allergy medicine like Benadryl)

  21. How do you feed a child medicine when one tablet is too strong?

  22. Liquid dose for children has been diluted to 12.5 mg for every 5 mL of medicine

  23. What percent by mass of diphenhydramine hydrochloride is in the solution? Liquid dose for children has been diluted to 12.5mg for every 5mL of medicine .0125 g = .250% (m/v) 5 mL 100

  24. EX 3: A saline solution containing 3.5 g of NaCl in 62.5 mL of solution. What is the percent of NaCl, by mass. ? % = 3.5 g NaCl 5.60% 100 62.5 mL solution

  25. EX 3: A saline solution containing 3.5 g of NaCl in 62.5 mL of solution. What is the percent of NaCl, by mass. ? % = 3.5 g NaCl 5.60% 100 62.5 mL solution

  26. Ex 4: What volume of ethanol is needed to produce 120 mL of a 22.3% (v/v) ethanol solution? %(v/v)= 26.8 mL 22.3 % = ethanol by volume (v/v) ? mL ethanol 100 120 mL solution

  27. Ex 5: What volume of a 2.8% (m/v) glucose solution would you need to deliver to a patient who needs 750 mg of glucose? 2.8 % = 0.750 g glucose glucose by volume (m/v) 100 ? mL glucose solution 26.8 mL

  28. Practice • If 10 mL of pure acetone is diluted with water to a total solution volume of 200 mL, what is the percent by volume of acetone in the solution? 2. A bottle of hydrogen peroxide is labeled 3.0% (v/v). How many mL of H2O2 are in a 400.0 mL bottle of this solution? 3. Calculate the grams of solute required to make 250 g of 0.10% MgSO4 (m/m). 4. A solution contains 2.7 g CuSO4 in 75 mL of solution. What is the percent (m/v) of the solution?

  29. If 10 mL of pure acetone is diluted with water to a total solution volume of 200 mL, what is the percent by volume of acetone in the solution? %(v/v)= ? % = 10 mL acetone 5.00 % acetone by volume (v/v) 100 200 mL solution

  30. 2. A bottle of hydrogen peroxide is labeled 3.0% (v/v). How many mL of H2O2 are in a 400.0 mL bottle of this solution? %(v/v)= 3.00 % = ? mL H2O2 12.0 mL H2O2 by volume (v/v) 100 400. mL solution

  31. 3. Calculate the grams of solute required to make 250 g of 0.10% MgSO4 (m/m). %(m/m)= 0.10 % = ? g MgSO4 0.250 g MgSO4 by volume (v/v) 100 250 g solution

  32. 4. A solution contains 2.7 g CuSO4 in 75 mL of solution. What is the percent (m/v) of the solution? %(m/v)= ? % = 2.7 g CuSO4 3.60 % CuSO4 by volume (m/v) 100 75 mL solution

  33. Practice • If 10 mL of pure acetone is diluted with water to a total solution volume of 200 mL, what is the percent by volume of acetone in the solution? 2. A bottle of hydrogen peroxide is labeled 3.0% (v/v). How many mL of H2O2 are in a 400.0 mL bottle of this solution? 3. Calculate the grams of solute required to make 250 g of 0.10% MgSO4 (m/m). 4. A solution contains 2.7 g CuSO4 in 75 mL of solution. What is the percent (m/v) of the solution? 5.00% acetone (v/v) 12.0mL H2O2 0.250g MgSO4 3.60% (m/v)

  34. B. Molarity

  35. Molarity • Molarity (M) is the number of moles of a solute dissolved per liter of solution.

  36. Molarity • Molarity is also known as molar concentration and is read as “ __#__ molar” (Ex. a 2M HCl solution is read as two molar HCl” • Note that the volume involved is the total volume of solution, not just the solvent.

  37. Molarity Molarity (M) = moles of soluteM = mol Liters of solution 1 L *if given grams, convert if to moles using the molar mass of the substance

  38. Why are grams important? • You can not directly measure moles, you must calculate the mass in grams first Moles Grams Molar mass ___g = 1 mole

  39. How to Prepare a Solution To make 1.00 liter of a 1.00 molar (1.0 M) solution: 1) add 1.0 mol of solute to a volumetricflask 2) add about ¼ flask of distilled water. Swirl the flask till the solute is dissolved. 3) slowly add water until the final volume reads 1.00 L

  40. Molarity EX 1. What is the molarity of a solution that contains 8 moles of CaCl2 in 50 mL of solution? mol 8 mol M = 160M CaCl2 L 1 0.05 L

  41. Molarity EX 2. How many grams of NaCl are needed to make 500mL of a 0.2 M solution? .2 M ? mol .1 mol M = L 1 0.5 L 0.1 mol NaCl 58.443 g NaCl =5.84 mol NaCl 1 mol NaCl

  42. Using Molarity Ex 3: A saline solution contains 0.90 g NaCl in exactly 100 mL of solution. What is the molarity of the solution? Step 1: Calculate # moles 0.90g NaCl x =0.0154 mol NaCl 1 mol NaCl 58.443 g NaCl Step 2: mL  L 100 mL x 1 L = 0.100 L NaCl 1000 mL

  43. Ex 3 continued Step 3: Calculate Molarity 0.154 M ? M 0.0154 mol M = L 1 0.1 L

  44. Ex 2: How many grams of solute are present in 562 mL of 0.24 M Na2SO4? M = mol mol = M L • L mol = 0.24M Na2SO4 x .562L = 0.135mol

  45. Convert from Moles to Grams 0.135mol Na2SO4 | 142g Na2SO4= | 1 mol Na2SO4 = 19.2g Na2SO4

  46. Practice • A solution has a volume of 2.0 L and contains 36.0 g of glucose. If the molar mass of glucose is 180 g/mol, what is the molarity of the solution? 0.100M glucose 2. How many moles of ammonium nitrate are in 335 mL of 0.425 M NH4NO3? 0.142mol NH4NO3 3. How many grams of solute are in 250 mL of 2.0 M CaCl2 solution? 55.5gCaCl2 4. Describe how you would prepare 250 mL of a 0.2 M NaOH solution. Need 2.00g NaOH in 250mL of solution

  47. 1. A solution has a volume of 2.0 L and contains 36.0 g of glucose. If the molar mass of glucose is 180 g/mol, what is the molarity of the solution? Molarity = mol L Glucose = C6H12O6 • Molar mass = 6(12.01g) + 12(1.008g) + 6(15.999g) = Calculate moles: 36.0g C6H12O6 | 1 mol C6H12O6 = mol C6H12O6 | XXX g C6H12O6 Calculate Molarity: XXXmol C6H12O6 = 0.100M glucose 2.0 L

  48. C. Dilutions

More Related