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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 1 Chapter 8 Solutions 8.4 Percent Concentration.

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Presentation on theme: "General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 1 Chapter 8 Solutions 8.4 Percent Concentration."— Presentation transcript:

1 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 1 Chapter 8 Solutions 8.4 Percent Concentration

2 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 2 The concentration of a solution  is the amount of solute dissolved in a specific amount of solution concentration =amount of solute amount of solution Concentration

3 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 3 Mass percent (m/m) concentration is  the percent by mass of solute in a solution  calculated using the formula: Mass = mass of solute(g) x 100% percent mass of solute(g) + mass of solvent(g) Mass percent = mass of solute(g) x 100% mass of solution(g) Mass Percent Concentration

4 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 4 Mass of Solution

5 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 5 The calculation of mass percent (m/m) requires the  grams of solute (g of KCl) and  grams of solution (g of KCl solution) g of KCl = 8.00 g g of solvent (water) = g g of KCl solution = g 8.00 g of KCl (solute) x 100% = 16.0% (m/m) g of KCl solution Calculating Mass Percent

6 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Guide to Calculating Solution Concentrations 6

7 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 7 A solution is prepared with 15.0 g of Na 2 CO 3 and 235 g of H 2 O. What is the mass percent (m/m) of the solution? 1) 15.0%(m/m) Na 2 CO 3 2) 6.38%(m/m) Na 2 CO 3 3) 6.00%(m/m) Na 2 CO 3 Learning Check

8 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 8 3) 6.00% (m/m) Na 2 CO 3 STEP 1 Given: 15.0 g of Na 2 CO 3 ; 235 g of H 2 O Need: mass percent (m/m) of Na 2 CO 3 solution STEP 2 Plan: mass percent(m/m) = g of solute x 100% g of solution Calculate mass of solution = 15.0 g g = 250 g of Na 2 CO 3 solution Solution

9 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 9 STEP 3 Write equalities and conversion factors: 15.0 g of Na 2 CO 3 = 250 g of solution 15.0 g Na 2 CO 3 and 250 g solution 250 g solution 15.0 g of Na 2 CO 3 STEP 4 Set up problem: mass = 15.0 g Na 2 CO 3 x 100 = 6.00%(m/m) Na 2 CO 3 percent 250 g solution (m/m) Solution (continued)

10 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 10 The volume percent (v/v) is  percent by volume of solute (liquid) in a solution  volume % (v/v) = volume of solute x 100% volume of solution  volume solute (mL) in 100 mL of solution. volume % (v/v) = mL of solute 100. mL of solution Volume Percent

11 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 11 The mass/volume percent (m/v) is  mass/volume % (m/v) = grams (g) of solute x 100% volume(mL) of solution  mass of solute(g) in 100 mL solution = g of solute 100. mL of solution Mass/Volume Percent

12 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Preparation of a Solution: Mass/Volume Percent 12

13 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 13 Percent Conversion Factors  Two conversion factors can be written for each type of percent concentration.

14 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 14 Write two conversion factors for each solution: A. 8.50% (m/m) NaOH B. 5.75% (v/v) ethanol C. 4.8% (m/v) HCl Learning Check

15 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 15 A. 8.50% (m/m) NaOH 8.50 g NaOH and 100 g solution 100 g solution 8.50 g NaOH B. 5.75% (v/v) ethanol 5.75 mL ethanol and 100 mL solution 100 mL solution 5.75 mL ethanol C. 4.8% (m/v) HCl 4.8 g HCl and 100 mL HCl 100 mL solution 4.8 g HCl Solution

16 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Guide to Using Concentration to Calculate Mass or Volume 16

17 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. How many grams of NaCl are needed to prepare 225 g of a 10.0% (m/m) NaCl solution? STEP 1 Given: 225 g of solution; 10.0% (m/m) NaCl Need: g of NaCl(solute) STEP 2 Plan: g of solution g of NaCl Example of Using Percent Concentration (m/m) Factors 17

18 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Solution STEP 3 Write equalities and conversion factors: 10.0 g of NaCl = 100 g of NaCl solution 10.0 g NaCl and 100 g NaCl solution 100 g NaCl solution 10.0 g NaCl STEP 4 Set up problem to cancel grams of solution: 225 g NaCl solution x 10.0 g NaCl = 22.5 g of NaCl 100 g NaCl solution 18

19 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 19 How many grams of NaOH are needed to prepare 75.0 g of 14.0% (m/m) NaOH solution? 1) 10.5 g of NaOH 2) 75.0 g of NaOH 3) 536 g of NaOH Learning Check

20 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Solution STEP 1 Given: 75.0 g of NaOH solution; 14.0% (m/m) NaOH solution Need: g of NaOH (solute) STEP 2 g of solution g of NaOH STEP 3 Write equalities and conversion factors: 14.0 g of NaOH = 100 of NaOH solution 14.0 g NaOH and 100 g NaOH solution 100 g NaOH solution 14.0 g NaOH STEP 4 Set up problem to cancel the grams of solution: 75.0 g NaOH solution x 14.0 g NaOH = 10.5 g of NaOH 100 g NaOH solution 20

21 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 21 How many milliliters of a 5.75% (v/v) ethanol solution can be prepared from 2.25 mL of ethanol? 1) 2.56 mL 2) 12.9 mL 3) 39.1 mL Learning Check

22 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Solution STEP 1 Given: 2.25 mL of ethanol (solute) 5.75% (v/v) ethanol solution Need: mL of ethanol solution STEP 2 Plan: mL of ethanol mL of solution STEP 3 Write equalities and conversion factors: 100 mL of solution = 5.75 mL of ethanol 5.75 mL ethanol and 100 mL solution 100 mL solution 5.75 mL ethanol STEP 4 Set up problem to cancel the mL of ethanol: 2.25 mL ethanol x 100 mL solution = 39.1 mL of solution mL ethanol 22

23 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. How many mL of a 4.20% (m/v) will contain 3.15 g KCl? STEP 1 Given: 3.15 g of KCl (solute) 4.20% (m/v) KCl solution Need: mL of KCl solution STEP 2 Plan: g of KCl mL of KCl solution Example Using Percent Concentration (m/v) Factors 23

24 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 24 STEP 3 Write equalities and conversion factors: 4.20 g KCl = 100 mL of KCl solution 4.20 g KCl and 100 mL KCl solution 100 mL KCl solution 4.20 g KCl STEP 4 Set up the problem: 3.15 g KCl x 100 mL KCl solution = 75.0 mL of KCl 4.20 g KCl Using Percent Concentration(m/v) Factors (continued)

25 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. 25 Learning Check How many grams of NaOH are needed to prepare 125 mL of a 8.80% (m/v) NaOH solution? 1) 7.04 g of NaOH 2) 11.0 g of NaOH 3) 14.2 g of NaOH

26 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Solution 26 2) 11.0 g of NaOH STEP 1 Given: 125 mL of NaOH (solution) 8.80% (m/v) NaOH solution Need: g of NaOH (solute) STEP 2 Plan: mL of NaOH solution g of NaOH

27 General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Solution (continued) 27 STEP 3 Write equality and conversion factors: 8.80 g of NaOH = 100 mL of NaOH solution 8.80 g NaOH and 100 mL NaOH solution 100 mL NaOH solution 8.80 g NaOH STEP 4 Set up the problem: 125 mL NaOH solution x 8.80 g NaOH 100 mL NaOH solution = 11.0 g of NaOH


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