Aqueous Solutions Unit

Name AQUEOUS SOLUTIONS UNIT Electrolytes & Molarity Definitions Solute – component in a solution that is present in lesser quantities (typically referred to as the solid that is dissolved in aqueous solutions)

Solvent – component in a solution that is present in larger quantities (water for aqueous solutions)

Aqueous solution – solution in which water is the dissolving substance

Ionizes – breaks into its constituent ions

Electrolytes – substances which dissociate into constituent ions in water to yield a solution that conducts electricity

Strong electrolytes – substances which completely dissociate in water & are good conductors of electricity

Weak electrolytes –substances which do not completely dissociate in water & weakly conduct electricity

Nonelectrolytes - substances with do not dissociate (produce ions) in water & do not conduct electricity

Electrolyte Practice problems: Assume all are strong electrolytes. Practice: Z Ch4 23-26 24a) iv b) ii c) iii d) i ii, acetic acid only partially dissociates (weak) 26) check with MsO Molarity Molarity – an expression of the concentration of a solute in solution defined as the moles of solute per liter of solution.

Eg. 1 Determine the molarity of a solution made 1.461 g NaCl in enough H2O to make 250.0L of solution.

Eg. 2 A solution is made by dissolving 3.550g of Na2SO4 in water using a 100.0mL volumetric flask to adjust the final volume. What is the molarity of this solution?

What is the concentration of Na ions in this solution?

Eg. 3 How many mL of 0.250 M NaCl solution must be measured to obtain 0.100 mol of NaCl?

Eg. 4 Calculate the number of mol of AgNO3 in 25 mL of 0.75 M AgNO3.

Eg. 5 Typical blood serum is about 0.14 M NaCl. What volume of blood contains 1.0 mg NaCl? Eg. 6 A student needs to prepare 250 mL of 0.100 M Cd(NO3)2 (MM=236.43) solution. How many g of the solid are required?

Eg. 7 Formalin is an aqueous solution of formaldehyde (HCHO). At high concentrations it is used as a preservative for biologic specimens. How many grams of formaldehyde are contained in 2.5 L of 12.3 M formalin?

Practice: Z Ch4 27to29 30ab 32 33 28) 5.2M C2H5OH 30a) 2.00M b) 1.00M 32) ask MsO