Chem 1075 Chapter 14 Solutions Lecture Outline Slide 2 Solutions A solution is a. A solution is composed of a dissolved in a. Solutions exist in all three physical states: Slide 3 Polar Molecules When two liquids make a solution, the solute is the quantity, and the solvent is the quantity. Recall, that a is present in a polar molecule. Water is a molecule. Slide 4 Polar & Nonpolar Solvents A liquid composed of molecules is a. Water and methanol are polar solvents. A liquid composed of molecules is a. Hexane is a nonpolar solvent.
Slide 5 Like Dissolves Like solvents dissolve in one another. solvents dissolve in one another. This it the like dissolves like rule. Methanol dissolves in water but hexane does not dissolve in water. Hexane dissolves in toluene, but water does not dissolve in toluene. Slide 6 Miscible & Immiscible Two liquids that completely in each other are liquids. Two liquids that are in each other are liquids. Polar water and nonpolar oil are liquids and to form a solution. Slide 7 Like Dissolves Like for Solids, like sodium chloride, are soluble in solvents and insoluble in nonpolar solvents., like table sugar (C 12 H 22 O 11 ), are soluble in solvents and insoluble in nonpolar solvents., like naphthalene (C 10 H 8 ), are soluble in solvents and insoluble in polar solvents. Slide 8 The Dissolving Process When a soluble crystal is placed into a solvent, it begins to. When a sugar crystal is placed in water, the water molecules attack the crystal and begin and into solution. The sugar molecules are held within a cluster of water molecules called a. Slide 9 Dissolving of Ionic Compounds
When a sodium chloride crystal is place in water, the water molecules of the crystal. In an ionic compound, the water molecules pull off of the crystal. The are surrounded by the charged hydrogens on water. The are surrounded by the charged oxygen on water. Slide 10 Rate of Dissolving There are three ways we can speed up the rate of dissolving for a solid compound. 1. Heating the solution: This increases the of the solvent and the solute is attacked by the solvent molecules. 2. Stirring the solution: This increases the between solvent and solute molecules. 3. Grinding the solid solute: There is more for the solvent to attack. Slide 11 Solubility and Temperature The solubility of a compound is the amount of solute that can dissolve in of water at a given. In general, a compound becomes more as the increases. Slide 12 Saturated Solutions A solution containing the amount of solute at a given temperature is a saturated solution. A solution that contains than the amount of solute is an unsaturated solution. Under certain conditions, it is possible to the solubility of a compound. A solution with greater than the maximum amount of solute is a supersaturated solution.
Slide 13-14 Supersaturated Solutions & Supersaturation At 55 C, the solubility of NaC 2 H 3 O 2 is 100 g per 100 g water. If a saturated solution at 55 C is cooled to 20 C, the solution is supersaturated. Supersaturated solutions are. The excess solute can readily be precipitated. A of sodium acetate added to a supersaturated solution of sodium acetate in water causes the to rapidly from the solution. Slide 15 Concentrations of Solutions The concentration of a solution tells us how much is dissolved in a given quantity of. We often hear imprecise terms such as a dilute solution or a concentrated solution. There are two precise ways to express the concentration of a solution: 1. 2. Slide 16 Mass Percent Concentration Mass percent concentration compares the mass of to the mass of The mass/mass percent (m/m %) concentration is the mass of solute dissolved in 100 g of solution. Slide 17 Calculating Mass/Mass Percent A student prepares a solution from 5.00 g NaCl dissolved in 97.0 g of water. What is the concentration in m/m %?
Slide 18 Mass Percent Unit Factors We can write several unit factors based on the concentration 4.90 m/m% NaCl: Slide 19 Mass Percent Calculation What mass of a 5.00 m/m% solution of sucrose contains 25.0 grams of sucrose? Slide 20 Molar Concentration The molar concentration, or molarity (M), is the number of of solute per of solution, is expressed as moles/liter. Molarity is the most commonly used unit of concentration Slide 21 Calculating Molarity What is the molarity of a solution containing 18.0 g of NaOH in 0.100 L of solution? Slide 22 Molarity Unit Factors We can write several unit factors based on the concentration 4.50 M NaOH:
Slide 23 Molar Concentration Problem How many grams of K2Cr2O7 are in 250.0 ml of 0.100 M K2Cr2O7? Slide 24 Molar Concentration Problem What volume of 12.0 M HCl contains 7.30 g of HCl solute (MM = 36.46 g/mol)? Slide 25 Dilution of a Solution Rather than prepare a solution by dissolving a solid in water, we can prepare a solution by a more concentrated solution. When performing a dilution, the does not change, only the amount of. The equation we use is: Slide 26 Dilution Problem What volume of 6.0 M NaOH needs to be diluted to prepare 5.00 L if 0.10 M NaOH?