2 Section 2 - Concentration and Molarity In a solution, the solute is distributed evenly throughout the solvent. Thismeans that any part of a solution has the same ratio of solute to solvent asany other part of the solution. This ratio is the concentration of the solution.Calculating ConcentrationParts Per MillionConcentrations can be expressed in many forms. One unit of concentrationused in pollution measurements that involve very low concentrations isparts per million, or ppm. Parts per million is the number of grams of solutein 1 million grams of solution. For example, the concentration of lead indrinking water may be given in parts per million.
3 Formula for Parts Per Million from reference table. Used for concentration that are very small.
4 MolarityIt is often convenient for chemists to discuss concentrations in terms of thenumber of solute particles in solution rather than the mass of particles insolution. Since the mole is the unit chemists use to measure the numberof particles, they often specify concentrations using molarity. Molaritydescribes how many moles of solute are in each liter of solution.The symbol M is read as “molar” or as “moles per liter.” Any amount ofthis solution has the same ratio of solute to solution.
5 Calculating with Molarity In working with solutions in chemistry, you will find that numericalCalculations often involve molarity. The key to all such calculations is thedefinition of molarity, which is stated as an equation below from the referencetable.
6 Dilution: The process of adding more solvent to a solution. Dilution Formula:M1 = Initial Molarity of solutionV1 = Initial Volume of solutionM2 = Final Molarity of solutionV2 = Final Volume of solutionM1V1 = M2V2
7 Questions:When 0.50 liter of a 12 M solution is diluted to 1.0 liters, the molarity of thenew solution isMM3. 12 M4. 24 MThe molarity (M) of a solution is equal to the1. number of grams of solute/liter of solvent2. number of grams of solute/liter of solution3. number of moles of solute/liter of solvent4. number of moles of solute/liter of solutionWhat is the total number of grams of NaOH (formula mass = 40.) neededto make 1.0 liter of a 0.20 M solution?gggg
8 What is the molarity of a solution that contains 30. grams of NaOH in 500. milliliters of solution?MMMMWhen 20. milliliters of 1.0 M HCL is diluted to a total volume of 60. milliliters,the concentration of the resulting solution isMMMMHow many liters of a 0.5 M sodium hydroxide solution would contain 2 molesof solute?1. 1L2. 2L3. 3L4. 4L
9 What is the concentration of 10. moles of copper (II) nitrate in 5 What is the concentration of 10. moles of copper (II) nitrate in 5.0 litersof solution?MMMMWhich solution is the most concentrated?1. 1 mole of solute dissolved in 1 liter of solution2. 2 moles of solute dissolved in 3 liters of solution3. 6 moles of solute dissolved in 4 liters of solution4. 4 moles of solute dissolved in 8 liters of solutionWhat is the total number of moles of H2SO4 needed to prepare 5.0 litersof a 2.0 M solution of H2SO4?1. 2.52. 5.03. 10.4. 20.
10 How many moles of solute are contained in 200 milliliters of a 1 M solution? 1. 12. 0.23. 0.84. 200What is the molarity of a solution that contains 0.50 mole of NaOHin 0.50 liter of solution?MMMMWhat is the molarity of a solution of NaOH if 2 liters of the solutioncontains 4 moles of NaOH?M 2. 2 M 3. 8 M 4. 80 M
11 A town located downstream from a chemical plant was concerned about fluoride ions from the plant leaking into its drinking water. According to theEnvironmental Protection Agency, the fluoride ion concentration in drinkingwater cannot exceed 4 ppm. The town hired a chemist to analyze its water.The chemist determined that a 175-gram sample of the town's watercontains gram of fluoride ions. How many parts per million offluoride ions are present in the analyzed sample?1.43 ppmWhat is the concentration of a solution, in parts per million, if 0.02 gramof Na3PO4 is dissolved in 1000 grams of water?1. 20 ppm2. 2 ppmppmppm
12 If 0. 025 gram of Pb(NO3)2 is dissolved in 100 If gram of Pb(NO3)2 is dissolved in 100. grams of H2O, what is theconcentration of the resulting solution, in parts per million?ppmppmppmppmAn aqueous solution has gram of oxygen dissolved in grams ofwater. Calculate the dissolved oxygen concentration of this solution inparts per million.7.0 ppmAn aqueous solution contains 300. parts per million of KOH. Determinethe number of grams of KOH present in grams of this solution.0.300 grams