1. Solution Concentration Chemistry

2. Ways to Express Solution Composition Molarity: Mass %: Volume %: Parts per million (ppm):

3. Molarity Most common unit of concentration 1. What is the molarity if 3 mol NaCl are dissolved to a total volume of 6 L? 2. How many grams of CuCl 2 are needed to make 500 mL of a 3.0 M solution?

4. Mass % 1. Determine the %(m/m) of copper in a 2.0 g penny that contains 1.8 g of copper. 2. If 10 g of salt is mixed with 90 g of water, what is the %(m/m) salt in the solution?

5. Volume % 1. How many mL of Alcohol are in 750 mL of Everclear (95% alcohol v/v)? 2. If you mix 20 mL of syrup with 60 mL of water, what is the % v/v of the resulting solution?

6. ppm ppm = parts per million Convert everything to mg/L 1. If you disolve 20 mg of NaCl in 2 L of water, what is the ppm NaCl? 2. Cl 2 gas is toxic at 30 ppm. If 5.0 kg of Cl 2 are released in a 10,000 L room, would it be at toxic levels?

7. Concentration Problems 1) What would be the molarity of a solution made with 25.0 g of KBr in 650 mL of solution? 25.0 g KBr x 1 mole KBr/ 119.0 g = 0.210 moles 650 mL x 1 L / 1000 mL = 0.650 L.210 moles / 0.650 L = 0.323 M 2) How many grams of Na 2 CO 3 are in 65 mL of.25 M solution? 65 mL x 1 L / 1000 mL = 0.065 L 0.25 mol/L x 0.065 L = 0.016 moles 0.016 moles x 106.0 g / mol = 1.70 g Na 2 CO 3

8. Concentration Problems 3) What would the mass % AgNO 3 be for a solution composed of 34.0 g of AgNO 3 in 450. g of methanol? 34.0 g / 34.0g + 450 g = 0.070 x 100 = 7.0 % 4) How many grams of acetic acid would you add to make 600 g of a 15 % solution by weight? 0.15 = x / 600 x = (0.15)(600) = 90 g

9. Concentration Problems 5) If 80.0 mL of water is added to 60.0 mL of acetone what is the % by volume of acetone? 80.0 mL + 60.0 mL = 140. mL 60.0 mL / 140. mL =.429 x 100 = 42.9% 6) Rubbing alcohol is an 85% solution by volume. If there is 150 mL of solution, how much isopropanol is there in the solution?.85 = x / 150 x = (.85)(150) = 127.5 mL

10. Dilutions Dilution – adding H 2 O to lower the concentration Volume x molarity = moles The # of mol of solute stays the same!!!! Volume 1 x Molarity 1 = Volume 2 x Molarity 2

11. Dilution Equation and problem If 30.0 mL of 0.0500 M HCl is added to 270. mL of water, what is the resulting concentration of the HCl solution?

12. Concentration Problem 0.550 L of a 0.500 mol /L NaCl solution sits on a hotplate overnight and 100. ml of water evaporates. What is the new concentration of NaCl in the solution?

13. Mole Fraction X = moles solute moles solute and solvent X is just a number with no units 1) What is the mole fraction of each component 0.45 moles of MgCl 2 in 180g H 2 O?