Solution Concentration: Molarity and Molality

Concentration of Solutions: Molarity, Molality, Mole Fraction

• To prepare 400.0 g of a 10.0% nitric acid (HNO3) solution by mass, 58.8 g of a concentrated nitric acid solution (68.0% HNO3 by mass) is needed.
• 375 g of a 4.00% NaOH solution by mass contains 15.0 g of NaOH.
• A throat spray containing 1.40% by mass phenol (C6H5OH) in water with a density of 0.9956 g/mL has a molarity of 0.15 M.
• To prepare 1.00 L of a 10.0% NaOH solution by mass with a density of 1.109 g/mL, 114 g of solid NaOH (97.0% NaOH by mass) is required.
• In a solution of 14.5 g of H3PO4 in 125 g of water, the mole fractions of H3PO4 and water are 0.0209 and 0.9791, respectively.
• A concentrated solution of nitric acid (68.0% HNO3 by mass) requires determination of the mole fractions and molality of HNO3 and water.
• For an acid solution used in an automobile battery containing 583 g of H2SO4 in 1.50 kg of water, the mole fractions are 0.067 for H2SO4 and 0.933 for water.
• For a solution of sodium chloride for intravenous injection containing 0.86 g of NaCl in 1.00 × 102 g of water, the mole fractions are 0.0026 for NaCl and 0.9974 for water.
• For a solution containing 46.85 g of codeine (C18H21NO3) in 125.5 g of ethanol (C2H5OH), the mole fractions are 0.054 for codeine and 0.946 for ethanol.
• For a solution containing 25 g of I2 in 125 g of ethanol (C2H5OH), the mole fractions are 0.035 for I2 and 0.965 for ethanol.
• For a saturated solution at 0 °C containing 0.710 kg of sodium carbonate (Na2CO3) in 10.0 kg of water, the mole fraction of Na2CO3 is 0.0119 and water is 0.988.
• For a mixture used to make an instant ice pack containing 125 g of NH4NO3 in 275 g of water, the mole fraction of NH4NO3 is 0.09927 and water is 0.907.
• For a solution containing 25 g of Cl2 in 125 g of dichloromethane (CH2Cl2), the mole fraction of Cl2 is 0.192 and dichloromethane is 0.808.
• For a solution containing 0.372 g of histamine (C5H9N) in 125 g of chloroform (CHCl3), the mole fraction of histamine is 0.00426 and chloroform is 0.997.
• 1 M and 1 m solutions refer to molarity and molality respectively, which are different ways of expressing the concentration of a solution.
• The molality of phosphoric acid (H3PO4) in a solution of 14.5 g of H3PO4 in 125 g of water is 1.176 mol/kg.
• A 13.0% solution of K2CO3 by mass with a density of 1.09 g/cm3 has a molality of 1.081 mol/kg.
• A solution of 0.444 mol of CoCl2 in 0.654 L has a molarity of 0.679 M.
• A solution of 98.0 g of phosphoric acid (H3PO4) in 1.00 L has a molarity of 1.0 M.
• A solution of 0.2074 g of calcium hydroxide (Ca(OH)2) in 40.00 mL has a molarity of 0.06998 M.
• A solution of 10.5 kg of Na2SO4.10H2O in 18.60 L has a molarity of 1.75 M.
• A solution of 7.0 × 10–3 mol of I2 in 100.0 mL has a molarity of 0.070 M.
• A solution of 1.8 × 104 mg of HCl in 0.075 L has a molarity of 6.6 M.
• 2.00 L of 18.5 M H2SO4 contains concentrated sulfuric acid with 37 mol, which equals 3.63x103 gm.
• 100.0 mL of 3.8 × 10–5 M NaCN contains the minimum lethal concentration of sodium cyanide in blood serum, with 3.8 × 10–6 mol or 1.9 × 10-4 g.
• 5.50 L of 13.3 M H2CO contains formaldehyde used to "fix" tissue samples, with 73.2 mol which equals 2.20kg.
• 325 mL of 1.8 × 10–6 M FeSO4 has the minimum concentration of iron sulfate detectable by taste in drinking water with 5.9 × 10–7 mol or 8.9 × 10–5 g.
• 1.6L is the volume of a 0.20-M K2SO4 solution that contains 57 g of K2SO4.
• 1.89 mL is the volume to which a 0.33-M C12H22O11 solution can be diluted to prepare 25 mL of a solution with a concentration of 0.025 M.