Solutions Section 2 Concentration Concentratio n Molarity Calculations

Solutions Section 2: Concentration Concentratio n • Molarity • Calculations • mol M = L

A. Concentration the amount of solute dissolved in a given amount of solvent Dilute – less solute Concentrated – more solute

B. Molarity (M) moles of solute per liter of solution Example: 3 M HCl 3 molar HCl 3 mol HCl 1 L

B. Molarity Preparing a Solution (in lab later) Make a 0. 5 M solution: 1)Add 0. 5 mol solute to 1 L volumetric flask. 2)Swirl to dissolve. 3)Fill with DI water exactly to the 1 L line. 1 2 3

C. Calculations Finding Molarity 1. What is the molarity of a solution containing 0. 900 g Na. Cl in 100 m. L of solution? 0. 900 g Na. Cl x 1 mol Na. Cl = 0. 0154 mol Na. Cl 58. 44 g Na. Cl 0. 0154 mol Na. Cl = 0. 154 M Na. Cl 0. 100 L 100 m. L = 0. 100 L

C. Calculations Finding Molarity 2. What is the molarity of a solution with a volume of 2. 00 L containing 36. 0 g of C 6 H 12 O 6 (glucose)? 36. 0 g C 6 H 12 O 6 x 1 mol C 6 H 12 O 6 = 0. 200 mol C 6 H 12 O 6 180. 18 g C 6 H 12 O 6 0. 200 mol C 6 H 12 O 6 0. 100 M C 6 H 12 O 6 = 2. 00 L

C. Calculations Finding Moles 3. How many moles of solute are in 3. 80 L of 0. 700 M Na. Cl. O (bleach)? 3. 80 L x 0. 700 mol Na. Cl. O = 1 L 0. 700 M written as mol/L 2. 66 mol Na. Cl. O

C. Calculations Finding Moles 4. How many moles of solute are in 250 m. L of 2. 20 M Ca. Cl 2? 0. 250 L x 2. 20 mol Ca. Cl 2 = 0. 550 mol Ca. Cl 2 1 L 250 m. L = 0. 250 L

C. Calculations Finding Mass (g) 5. What mass of sodium hydroxide (Na. OH) is needed to make 200 m. L of a 0. 150 M solution? 0. 200 L x 0. 150 mol Na. OH = 0. 0300 mol Na. OH 1 L 0. 0300 mol Na. OH x 40. 00 g Na. OH = 1. 20 g Na. OH 1 mol

C. Calculations Finding Volume (L) 6. How many liters of a 1. 15 M solution are needed to give 0. 805 moles of solute? 0. 805 mol x 1 L = 0. 700 L 1. 15 mol How many m. L are needed? 0. 700 L = 700 m. L