Solutions & Chemical Equilibrium Section 2: Concentration Concentration Molarity Calculations mol L M =

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

B. Molarity 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) To make a 0.5 M (0.5 molar) solution, first add 0.5 mol of solute to a 1 L volumetric flask half filled with distilled water.

B. Molarity Preparing a Solution (in lab later) Swirl the flask carefully to dissolve the solute.

B. Molarity Preparing a Solution (in lab later) Fill the flask with water exactly to the 1 L mark.

C. Calculations Finding Molarity What is the molarity of a solution containing 0.900 g NaCl in 100 mL of solution? 1 mol NaCl 58.44 g NaCl 0.900 g NaCl x = 0.0150 mol NaCl IV saline solution 0.0150 mol NaCl 0.100 L 0.150 M NaCl = 100 mL = 0.100 L

C. Calculations Finding Molarity What is the molarity of a solution with a volume of 2.00 L containing 36.0 g of C6H12O6 (glucose)? 1 mol C6H12O6 180.18 g C6H12O6 36.0 g C6H12O6 x = 0.200 mol C6H12O6 0.200 mol C6H12O6 2.00 L = 0.100 M C6H12O6

C. Calculations Finding Moles How many moles of solute are in 3.80 L of 0.700 M NaClO (bleach)? 0.700 mol NaClO 1 L 3.80 L x = 2.66 mol NaClO 0.700 M written as mol/L bleach

C. Calculations Finding Moles How many moles of solute are in 250 mL of 2.20 M CaCl2? 0.250 L x 2.20 mol CaCl2 = 1 L 0.550 mol CaCl2 250 mL = 0.250 L

C. Calculations Finding Mass (g) What mass of sodium hydroxide (NaOH) is needed to make 200 mL of a 0.150 M solution? 0.200 L x 0.150 mol NaOH = 1 L 0.0300 mol NaOH x 40.00 g NaOH = 1 mol 0.0300 mol NaOH bleach 1.20 g NaOH

C. Calculations Finding Volume (L) How many liters of a 1.15 M solution are needed to give 0.805 moles of solute? 0.805 mol x 1 L = 1.15 mol How many mL are needed? 0.700 L bleach 0.700 L = 700 mL