Molarity of Solution

Molarity of Solution Molarity (M) is one way of expressing the concentration or concentration of a solution. Molarity expresses the number of moles of solute per liter of solution. The units of molarity (M) are mol/liter or mmol/mL. with: M = molarity (mol/liter or M) n = number of moles of solute (mol) V = volume of solution (liters) Example 1. 1. Determine the Molarity of the Solution. What is the molarity of the solution prepared by dissolving 5.85 grams of NaCl (Ar Na = 23, Cl = 35.5) in 500 mL of water? Answer: 2. Determine the mass of the solute in a solution whose molarity is known. Calculate the mass of NaOH (Ar Na = 23, O = 16, and H = 1) that must be dissolved to make 100 mL of 0.1 M NaOH solution! Answer: Exercise 1. 1. Determine the molarity of the solution prepared by dissolving: a. 0.8 mol of NaCl in 250 mL of water b. 0.5 mol of KOH in 1000 mL of water 2. Determine the molarity of the solution prepared by dissolving: a. 50 grams of CaCO3 (ArCa = 40, C = 12, and O = 16) in 250 mL of water b. 11.6 grams Mg(OH)2 (Ar Mg = 24, O = 16, and H = 1) in 2 liters of water 3. How much water is needed to dissolve 2 moles of KOH (Ar K = 39, O = 16, and H = 1) to make a 0.05 M KOH solution? 4. What is the mass of the solute in 500 mL of 0.1 M Ca(OH)2 solution (Ar Ca = 40, O = 16, and H = 1)? Exercise 2. 1. Know the relative atomic masses (Ar ) C = 12, N = 14, O = 16, and H = 1. Determine the standard volume (STP) of: a. 4.4 grams of CO2 b. 4 moles O2 c. 6.8 grams of NH3 d. 1.806 × 1022 hydrogen molecules 2. It is known that ArC = 12, N = 14, O = 16, S = 16, H = 1, and Fe = 56. Determine the mass of: a. 4.48 liters of nitrous oxide gas (STP) b. 5 mol CO(NH2 )2 c. 0.6 moles of SO2 gas (RTP) d. 6.02 × 1021 iron atoms 3. Determine the number of particles from: a. 3 moles of H2O molecules b. 2 liters of oxygen gas at 27 °C and 1 atm pressure c. 3.2 grams of O2 (ArO = 16) d. 40 grams of CaCO3 (Ar Ca = 40, C = 12, and O = 16) e. 6.72 liters of NO2 gas (STP) 4. Determine the volume of 0.5 mol of CO gas measured at 30 °C and 1 pressure ATM! 5. What is the volume of 12.8 grams of SO2 gas (Ar S = 32, O = 16) measured at 28 °C and 1 atm pressure? 6. At a certain temperature and pressure (T, P), 2 moles of oxygen gas has a volume of 30 liters. At the same temperature and pressure, determine the volume of 5 moles of nitrogen gas! 7. At a certain temperature and pressure (T, P), 4.4 grams of CO2 has a volume of 10 liters. At the same temperature and pressure, determine the volume of 19.2 grams of SO2 gas (Ar C = 12, O = 16, and S = 32)! 8. Determine the relative atomic mass (Ar ) of 3.25 grams of metal X which has the number particles 3.01 × 1022 X atoms ! 9. How much mass of C6 H12O6 is needed to make 2 liters of 0.05 M C6 H12O6 solution (ArC = 12, H = 1, O = 16)? 10. Determine the molarity of the urea solution (CO(NH2 )2 ) (Ar C = 12, O = 16, N = 14, and H = 1) which is prepared by dissolving 24 grams in 500 mL of water!