Solution Concentration

Section 14.2

Concentration - amount of solute dissolved in a specific amount of solvent

concentrated - a lot of solutedilute - very little solute

Percent mass = mass of solute x100mass of solution

Example #1 - In order to maintain a sodium chloride solution similar to ocean water, an aquarium must contain 3.6g of NaCl per 100.0g of water. What is the % mass NaCl of the solution?

Percent mass = mass of solute x100mass of solution

% = 3.6 g x100 103.6g

= 3.5% Mass of solute + mass of solvent

Percent (m/v) = mass of solute x100volume of solution (in mL)

Example #2 – How many grams of solute are needed to prepare 2.00L of 2.00% glucose (m/v)

2.00% = g x100 2000mL

= 40.0 g

Molarity (M) = moles solute liters of solution

Example #3 - A 100.5 mL intravenous solution contains 5.10g of glucose (C6H12O6). What is the molarity of this solution?

Molarity (M) = moles solute liters of solution

5.10g C6H12O6 x __________g C6H12O6

mol C6H12O6

180.161

= 0.0283 mol

100.5 mL = .1005 L

M = 0.0283 mol 0.1005 L

= 0.282 mol/L or M

Example #3 - how would you prepare 2.00L of a 5.0M NaCl solution?

5.0 = mol 2.00 L

= 10. mol

10. mol NaCl x __________mol NaCl

g NaCl1

58.443

= 580 g NaCl

* to make the solution dissolve 584 g of NaCl in enough water to make 2.00 L of solution

Diluting Solutions- using a concentrated solution to make a diluted solution

M1V1 = M2V2

Example #4 - what volume, in milliliters, of 2.00 M calcium chloride stock solution would you use to make 0.50 L of 0.300M solution?M1V1 = M2V2

(2.00)(V1) = (.300)(.50)

V1 = (0.300)(0.50L)(2.00)

V1 = 0.075L

0.075L = 75 mL