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Chapter 12 Solutions

Chapter 12 Solutions. 12.4 Percent Concentration. Percent Concentration. The concentration of a solution is the amount of solute dissolved in a specific amount of solution amount of solute amount of solution

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Chapter 12 Solutions

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  1. Chapter 12 Solutions 12.4 Percent Concentration

  2. Percent Concentration The concentration of a solution • is the amount of solute dissolved in a specific amount of solution amount of solute amount of solution • as percent concentration describes the amount of solute that is dissolved in 100 parts of solution amount of solute 100 parts solution

  3. Mass Percent The mass percent (m/m) • concentration is the percent by mass of solute in a solution Mass percent (m/m) = mass of solute x 100% mass of solute + mass of solvent • is the g of solute in exactly100 g of solution Mass percent = g of solute x 100% 100. g of solution

  4. Calculating Mass Percent Mass percent (%m/m) is calculated from the grams of solute (g KCl) and the grams of solution (g KCl solution). g of KCl = 8.00 g g of solvent (water) = 42.00 g g of KCl solution = 50.00 g 8.00 g KCl (solute) x 100 = 16.0% (m/m) 50.00 g KCl solution

  5. Mass of Solution

  6. Calculating Solution Concentration

  7. Learning Check A solution is prepared by mixing 15.0 g of Na2CO3 and 235 g of H2O. Calculate the mass percent (m/m) of the solution. A. 15.0% (m/m) Na2CO3 B. 6.38% (m/m) Na2CO3 C. 6.00% (m/m) Na2CO3

  8. Solution STEP 1 Determine quantities of solute and solution. Mass of solute = 15.0 g of Na2CO3 Mass of water = 235 g of water Mass of solution = 250. g of Na2CO3 solution STEP 2 Write the % concentration expression. Mass percent (m/m) = grams of Na2CO3 x 100% grams of Na2CO3 solution

  9. Solution (continued) STEP 3Substitute solute and solution quantities into the expression Mass percent (m/m) = 15.0 g Na2CO3 x 100% 250. g Na2CO3 solution = 6.00% (m/m) Na2CO3 solution (C)

  10. Volume Percent The volume percent (v/v)is • percent volume (mL) of solute (liquid) to volume (mL) of solution Volume percent(v/v) = mL of solute x 100% mL of solution • solute (mL) in 100 mL of solution Volume percent (v/v) = mL of solute x 100% 100 mL of solution

  11. Volume Percent A volume percent (v/v)solution is prepared by • using a specific volume (mL) of solute (liquid) • adding water to the volume line

  12. Percent Conversion Factors • Two conversion factors can be written for each type of percent value.

  13. Learning Check Write two conversion factors for each solution. A. 8.50% (m/m) NaOH B. 5.75% (v/v) ethanol

  14. Solution A. 8.50% (m/m) NaOH solution 100 g of NaOH solution = 8.50 g of NaOH 8.50 g NaOH and 100 g NaOH solution 100 g NaOH solution 8.50 g NaOH B. 5.75% (v/v) ethanol solution 100 mL of ethanol solution = 5.75 mL of ethanol 5.75 mL ethanol and 100 mL solution 100 mL solution 5.75 mL ethanol

  15. Using Concentration to Calculate Mass or Volume

  16. Example of Using Percent Factors How many grams of NaCl are needed to prepare 225 g of a 10.0% (m/m) NaCl solution? STEP 1 State the given and needed quantities.Given 225 g of NaCl solution; 10.0% (m/m) NaCl solution Need grams of NaCl STEP 2Write a plan to calculate mass or volume. grams of NaCl solution grams of NaCl

  17. Example of Using Percent Factors (continued) STEP 3 Write equalities and conversion factors. 100 g of NaCl solution = 10.0 g of NaCl 10.0 g NaCl and 100 g NaCl solution 100 g NaCl solution 10.0 g NaCl STEP 4Set up problem to calculate mass or volume. 225 g NaCl solution x 10.0 g NaCl = 22.5 g of NaCl 100 g NaCl solution

  18. Learning Check How many grams of NaOH are needed to prepare 75.0 g of a 14.0% (m/m) NaOH solution? A. 10.5 g of NaOH B. 75.0 g of NaOH C. 536 g of NaOH

  19. Solution STEP 1 State the given and needed quantities. Given 75.0 g of NaOH of a 14.0% (m/m) solution Need grams of NaOH STEP 2Write a plan to calculate mass or volume. grams of NaOH solution grams of NaOH

  20. Solution (continued) STEP 3 Write equalities and conversion factors. 100 g of NaOH solution = 14.0 g of NaOH 14.0 g NaOH and 100 g solution 100 g solution 14.0 g NaOH STEP 4Set up problem to calculate mass or volume. 75.0 g solution x 14.0 g NaOH = 10.5 g of NaOH (A) 100 g solution 14.0 % (m/m) factor

  21. Learning Check How many milliliters of a 5.75% (v/v) ethanol solution can be prepared from 2.25 mL of ethanol? A. 2.56 mL B. 12.9 mL C. 39.1 mL

  22. Solution STEP 1 State the given and needed quantities. Given 2.25 ml of ethanol 5.75% (v/v) ethanol solution Need milliliters of ethanol solution STEP 2Write a plan to calculate mass or volume. mL of ethanol mL of ethanol solution

  23. Solution (continued) STEP 3 Write equalities and conversion factors. 100 mL of ethanol solution = 5.75 mL of ethanol 5.75 mL ethanol and 100 mL solution 100 mL solution 14.0 mL ethanol STEP 4Set up problem to calculate mass or volume. 5.75% (v/v) inverted 2.25 mL ethanol x 100 mL ethanol solution 5.75 mL ethanol = 39.1 mL of solution (C)

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