1. Concentration of Solutions

2. Concentration A measurement that describes how much solute is in a given amount of solvent or solution.A measurement that describes how much solute is in a given amount of solvent or solution. Many, many different units to express concentration. Pick the unit by the task at hand.Many, many different units to express concentration. Pick the unit by the task at hand.

3. Percent By mass By Volume Part over Whole times 100%.

4. Twists Sometimes they ask for the part or the whole, not the percent. Sometimes they give you the volume/mass of the solution; sometimes they give you the volume/mass of the solvent and the volume/mass of the solute. Mass solution = Mass solute + Mass solvent

5. Molarity (M) Molarity (M) = moles of solute liters of solution liters of solution Movie on Preparing Solutions

6. Recall the mole map! # of grams # of moles X F.M.  by F.M.

7. Twists must beSometimes they give moles of solute; sometimes they give grams of solute. Grams must be converted to moles. must beSometimes they give mL of solution instead of Liters. Milliliters must be converted to liters. Sometimes they ask for the grams or moles of solute or the volume, rather than the molarity.

8. Rearranging … Molarity (M) = # moles of solute liters of solution liters of solution Liters of solution = # of moles solute Molarity Molarity # of moles of solute = Molarity X Liters

9. PPM (parts per million) PPM = grams solute X 1,000,000PPM = grams solute X 1,000,000 Usually used when the solute is present in very small amounts.Usually used when the solute is present in very small amounts. (The Regents don’t follow this rule.)(The Regents don’t follow this rule.) grams solution

10. PPM (parts per million) PPM = grams solute X 1,000,000PPM = grams solute X 1,000,000 PPM is a ratio between the mass of the solute & the mass of the solution. Kind of like % except you multiply by 1,000,000 instead of 100. grams solution

11. About 0.0043 g of O 2 can be dissolved in 100 mL of water at 20 o C. Express in ppm. Remember 1 mL of water has a mass of 1 g. PPM = (0.0043g / 100.0043) X 1,000,000. PPM = 43 ppm

12. CO 2 gas has a solubility of 0.0972 g/100 g water at 40 o C. Express in parts per million. PPM = (0.0972 g / 100.0972 g solution) X 1,000,000. PPM = 971 ppm.

13. What is the concentration in ppm of a solution with 30.0 g NaNO 3 in 70.0 g water? PPM = (30.0 g NaNO 3 / 100.0 g solution) X 1,000,000. PPM = 300,000 = 3.0 X 10 5

14. How many grams of KOH are needed to be dissolved in water to make 2000.0 grams of a 10.0 ppm solution? 10 ppm = (? grams KOH / 2000.0 g solution) X 1,000,000. Divide both sides by 1,000,000. 1 X 10 -5 ppm = (? grams KOH / 2000.0 g soln.) Multiply both sides by 2000. 0.02 = grams KOH