Solutions Chapter 15

What are solutions? Solutions are homogenous mixtures containing two or more substances called the solute and the solvent. The solute is the substance that dissolves. The solvent is the dissolving medium. May exist as a solid, liquid, or gas

Solution Vocabulary A substance that dissolves in a solvent is soluble. A substance that does not dissolve in a solvent is insoluble. Immiscible describes two liquids that can be mixed together but separate after you cease mixing them. Two liquids that are soluble in each other are called miscible.

Why are substance soluble in one another whereas other are not? Attractive forces exist b/t the pure solute particles, b/t pure solvent particles, and b/t the solute and solvent particles. The process of surrounding solute particles with solvent particles to form a solution is solvation. “Like dissolves like”

Solubility Too much sugar in tea? Solubility is the maximum amount of solute that will dissolve in a given amount. Saturated solution-it contains the max amount of dissolved solute for a given amount of solvent Unsaturated solution-less dissolved solute for a given temperature and pressure

Factors that affect solubility Temperature and solubility-many substances are more soluble at high temp. Gases are less soluble at higher temperatures than lower temperatures. Supersaturated solution-contains more dissolved solute than a saturated solution at the same temperature. Rock candy and mineral springs

Pressure and Solubility The solubility of a gas in any solvent increases as it’s external pressure increases. Carbonated beverages depend on this fact. When the beverage is opened, the pressure of the gas in the space above decreases.

Using % to describe Concentration Percent by mass describes solutions in which a solid is dissolved in a liquid. Ratio of the solute’s mass to the solution’s mass expressed as a percent.

Problem Aquariums must keep sodium chloride similar to that of the ocean. If aquarium contains 3.6 g of NaCl per 100.0 g of water. What is the percent of mass of the NaCl in the solution? 3.5%

Molarity Molarity is the number of moles of solute dissolved per liter of solution. Also known as molar concentration. Must know the moles of solute. Must know the liters of solution.

Example Problem An intravenous (IV) solution contains 5.10 g of glucose in 100.5 mL of water. What is the molarity of the solution? .28M

Dilution Solution How do you calculate the molarity of 1L of a 1.5M aqueous solution of sucrose for an experiment? Use the Dilution formula. M1V1=M2V2 OR T-chart

Example Problems How many grams of Calcium Chloride would be dissolved in 1 L of .10M solutions of Calcium Chloride? 11 g Calcium Chloride A liter of 2M NaOH solution contains how many grams of NaOH? 80 g NaOH