Colegio Decroly Americano 10th and 11th Grade Chemistry Group Assessment Chapter #14 Solution Concentration Names: Diego Diaz, Diego Henkle, Diego Gudiel, Rodrigo Medrano Section 2 Solution Concentration: Practice Problems 9. What is the percent by mass of NaHCO 3 in a solution containing 20.0 g NaHCO 3 dissolved in 600.0 mL H 2 O? SOLUTION: 600.0 mL H 2 O x 1.0 g/mL = 600.0 g H 2 O 20 g NaHCO 3 / 600 g H 2 O + 20g NaHCO 3 x 100 = 3% 10. You have 1500.0 g of a bleach solution. The percent by mass of the solute sodium hypochlorite, NaOCl, is 3.62%.How many grams of NaOCl are in the solution? SOLUTION: 3.62% = 100 x mass NaOCl / 1500.0 g Mass NaOCl = 54.3 g 11. In question 10, how many grams of solvent are in the solution? SOLUTION: 1500.0 g - 54.3 g = 1445.7 solvent 12. Challenge The percent by mass of calcium chloride in a solution is found to be 2.65%. If 50.0 grams of calcium chloride is used, what is the mass of the solution? SOLUTION: Mass of Solution= 1886.79 g 2.65% = 100 x 50 g CaCl2 / 1886.79 g 13. What is the percent by volume of ethanol in a solution that contains 35 mL of ethanol dissolved in 155 mL of water? SOLUTION: 35 mL/ 155 mL+ 35 mL x 100 = 18% Answer = 18% 14. What is the percent by volume of isopropyl alcohol in a solution that contains 24 mL of isopropyl alcohol in 1.1 L of water? SOLUTION: 24 mL / 24 ml + 1100 mL x 100 = 2.1%
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15. Challenge If 18 mL of methanol are used to make an aqueous solution that is 15% methanol by volume, how many milliliters of solution are produced? SOLUTION: 15% = 18 mL / x mL solution x 100 x = 120 16. What is the molarity of an aqueous solution containing 40.0 g of glucose (C 6 H 12 O 6 ) in 1.5 L of solution? SOLUTION: mol C 6 H 12 O 6 = 40.0 g x 1 ml / 180.16 g = 0.222 mol molarity = mol C 6 H 12 O 6 / 1.5 L solution = 0.222 mol / 1.5 L = 0.15 M 17. Calculate the molarity of 1.60 L of a solution containing 1.55 g of dissolved KBr. SOLUTION: mol KBr = 1.55 g x 1 mol / 119 g = 0.0130 mol KBr molarity = mol KBr / 1.60 L solution = 0.0130 mol / 1.60 L = 8.13 x 10 -3 M 18. What is the molarity of a bleach solution containing 9.5 g of NaOCl per liter of bleach? SOLUTION: mol NaOCL = 9.5g x 1 mol / 74.44 g = 0.13 mol molarity = mol NaOCl / 1.00 L solution = 0.128 mol / 1.00 L = 0.13 M 19. Challenge How much calcium hydroxide (Ca(OH) 2 ), in grams, is needed to produce 1.5 L of a 0.25M solution? SOLUTION: 0.25 M = x mol Ca(OH) 2 / 1.5 L solution x = 0.38 mol Ca(OH) 2 0.38 mol Ca(OH) 2 x 74.08 g / mol = 28 g Ca(OH) 2 20. How many grams of CaCl 2 would be dissolved in 1.0 L of a 0.10M solution of CaCl 2 ? SOLUTION: mol CaCl 2 = (0.10M)(1.0 L) = (0.10 mol / k) (1.0 K) = 0.10 mol CaCl 2 mass CaCl 2 = 0.10 mol CaCl 2 x 110.98 g / 1 mol mass of CaCl 2 = 11g 21. How many grams of CaCl 2 should be dissolved in 500.0 mL of water to make a 0.20M solution of CaCl2? SOLUTION: 500ml x 1L / 1000 ml x 0.20 M = 0,10 mol 0.10 mol CaCl 2 = 0.10 mol CaCl 2 x 110.98g / 1mol mass of CaCl 2 = 11g 22. How many grams of NaOH are in 250 mL of a 3.0M NaOH solution? SOLUTION:
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Colegio Decroly Americano
10th and 11th Grade Chemistry
Group Assessment Chapter #14 Solution Concentration
Names: Diego Diaz, Diego Henkle, Diego Gudiel, Rodrigo Medrano
Section 2 Solution Concentration: Practice Problems
9. What is the percent by mass of NaHCO3 in a solution containing 20.0 g NaHCO3 dissolved in 600.0 mL
H2O?
SOLUTION:
600.0 mL H2O x 1.0 g/mL = 600.0 g H2O
20 g NaHCO3 / 600 g H2O + 20g NaHCO3 x 100 = 3%
10. You have 1500.0 g of a bleach solution. The percent by mass of the solute sodium hypochlorite, NaOCl, is
3.62%.How many grams of NaOCl are in the solution?
SOLUTION:
3.62% = 100 x mass NaOCl / 1500.0 g
Mass NaOCl = 54.3 g
11. In question 10, how many grams of solvent are in the solution?
SOLUTION:
1500.0 g - 54.3 g = 1445.7 solvent
12. Challenge The percent by mass of calcium chloride in a solution is found to be 2.65%. If 50.0 grams
of calcium chloride is used, what is the mass of the solution?
SOLUTION:
Mass of Solution= 1886.79 g
2.65% = 100 x 50 g CaCl2 / 1886.79 g
13. What is the percent by volume of ethanol in a solution that contains 35 mL of ethanol dissolved in 155 mL
of water?
SOLUTION:
35 mL/ 155 mL+ 35 mL x 100 = 18%
Answer = 18%
14. What is the percent by volume of isopropyl alcohol in a solution that contains 24 mL of isopropyl
alcohol in 1.1 L of water?
SOLUTION:
24 mL / 24 ml + 1100 mL x 100 = 2.1%
15. Challenge If 18 mL of methanol are used to make an aqueous solution that is 15% methanol by volume,
how many milliliters of solution ...
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