1. % by Mass Another way to measure the concentration of a solution % by mass = mass solute x 100 mass solution Solution = solute + solvent

2. Example What is the % by mass of a solution with 3.6 g of NaCl dissolved in 100.0 g of water? % = (3.6 / 103.6) x 100 = 3.5% NaCl

3. Example #2 Find the percent by mass of NaCl in 450.0 mL of a 0.85 M NaCl solution. The density of the solution is 1.04 g/mL % by mass = mass solute x 100 mass solution Step 1: Find mass of solute (NaCl) Step 2: Find mass of solution Step 3: Calculate % by Mass

4. Finding Mass of Solute Find the percent by mass of NaCl in 450.0 mL of a 0.85 M NaCl solution. The density of the solution is 1.04 g/mL Find Mass of Solute: Given: 450.0 mL of solution 0.85 M Find: Moles of NaCl and Convert to Grams M: moles of solute (n)/ liters of solution (L) n = 0.38 mole NaCl Mass = 22 g NaCl

5. Finding Mass of Solution Find the percent by mass of NaCl in 450.0 mL of a 0.85 M NaCl solution. The density of the solution is 1.04 g/mL Find Mass of Solution:  Given: 450.0 mL of solution  Density of solution = 1.04 g/mL  450.0 mL 1.04 g = 468.0 g solution 1 mL

6. Finding % by Mass Find the percent by mass of NaCl in 450.0 mL of a 0.85 M NaCl solution. The density of the solution is 1.04 g/mL Mass of Solute: 22 g NaCl Mass of Solution: 468.0 g solution % by mass = mass solute x 100 mass solution (22g NaCl /468.0 g solution) x 100 = 4.7%