Solutions Chapters 7 & 14 textbook

Hexane and Water demo

What did you observe and why?

Solutions Homogeneous mixture of substances in the same physical state Atoms, ions, or molecules of one substance (solute) are spread uniformly throughout a second substance (solvent) For example:

Types of solutions: solutions are not always solids dissolved in liquids- there are many types

Properties of Solutions Homogeneous mixtures Clear and do not disperse light Can be colored Will not settle on standing Will pass through a filter unchanged Some solutions are electrolytes

Solubility How much of a solute will dissolve in a certain amount of solvent at a certain temperature Soluble: materials with a high solubility; dissolves Insoluble: materials with low solubility

Factors that Affect Solubility Nature: “Like dissolves like”

Factors that Affect Solubility Temperature Solids become more soluble with increased temperature Gases become more soluble with decreased temperature Table F

Factors the Affect Solubility Pressure Little to no effect on solubility of solid or liquid solutes Increased pressure increases solubility of gases Decreased pressure decreases solubility of gases

Table F: Predicting Solubility Table F shows the general solubility rules for various solutes. Read the headings on the columns. Determine what they mean and how to apply the information to certain circumstances.

Solubility Curves: Table G Table G indicates the solubility of certain substances at different temperatures. Use the graph to determine if a solution is saturated, unsaturated or supersaturated Use the graph to determine how much solute can be dissolved

Concentration of Solutions Aside from using descriptive terms, like saturated, supersaturated and unsaturated, concentration can be quantified using molarity. Molarity (M): the number of moles of solute per liter of solution Molarity = moles of solute liters of solution

Practice Question What is the molarity of a solution that contains 4.0 molesof NaOH in .50L of solution?

Preparation of Solutions I want to make one liter of a 2M solution of NaCl(aq). Do I: Measure out 2 moles of NaCl and put it into a flask containing one liter of water Measure out 2 moles of NaCl, place it into a flask, and add enough water until the volume of the flask reads 1L

Molarity by Dilution M1V1 = M2V2 A substance with known molarity can be diluted to a different molarity using this formula

Molarity by Dilution Practice Problem If you dilute 175 mL of a 1.6 M solution of LiCl to 1.0 L, determine the new concentration of the solution.

Molality Moles of solute/kg of solvent Useful for large concentrations whereas

Molality Practice Problem Calculate the molality of a solution 8.53 g benzene, C6H6, dissolved in 20.6 g carbon tetrachloride CCl4.

Concentration of Solutions PPM – parts per million- used for solutions with extremely low concentrations ppm= mass of solute x 1,000,000 mass of solution

Practice Question What is the concentration in ppm of a 100 gram solution that contains 2.5 g of NaCl?

Colligative Properties properties of solutions that depend upon the ratio of the number of solute particles to the number of solvent molecules in a solution the presence of solute influences properties such as boiling point and freezing point Boiling point rises Freezing point decreases The number of particles in solute impacts the magnitude of change

Colligative Properties Which of the following will have the lowest freezing point? 1M C6H12O6 1M NaCl 1M CaCl2 (answer is C- more particles!)