Solubility Chapter 15.1 B

Vocabulary Word Solubility: the maximum amount of solute that dissolves in a given amount of solvent at a specific temperature and pressure

Solubility Every solute has a characteristic solubility

Solvation Particles of solvent collide with particles of solute  dissolving As more and more solute dissolves, some of the dissolved solute particles collide with the remaining crystalline solute  crystallization

Solvation As long as dissolving rate > crystallization rate more solute will continue to dissolve (unsaturated solution) Eventually dissolving rate = crystallization rate (dynamic equilibrium: saturated solution)

Factors Affecting Solubility Solubility is how much solute will dissolve (NOT how fast it dissolves) Temperature Pressure

Temperature Effects Many substances are more soluble at higher temperature More sugar or salt will dissolve in hot liquid than in cold liquid

Temperature Effects Gases are less soluble at higher temperatures As the temperature increases the kinetic energy increases. This allows gas particles to escape to the atmosphere

Temperature Effects

Supersaturated Solutions Since solubility of some solids increases with temperature: Allows the formation of supersaturated solutions Make a saturated solution at an elevated temperature Cool slowly

Vocabulary Word Supersaturated solution: a solution that contains more dissolved solute than a saturated solution at the same temperature.

Supersaturated Solutions Are unstable Add a seed of solute  crystallization

Supersaturated Solutions Are unstable Will crystallize on scratches of the container Will crystallize if tapped or stirred

Examples of Supersaturated solutions Cloud seeding: silver iodine is spread in the atmosphere to cause water particles in supersaturated air to condense and rain to fall

Examples of Supersaturated solutions Mineral springs have salt crystals along the edge

Examples of Supersaturated solutions Rock candy is made using a supersaturated solution of sugar water

Pressure Effects on Solubility Solubility of gaseous solutes increase with increasing pressure (the soft drink won’t go flat as quickly if the lid is kept on)

Pressure Effects on Solubility Soft drinks are carbonated at high pressure When the cap is unscrewed, gas escapes

Spangler Video Clip supersaturated solutions: http://www.stevespanglerscience.com/experiment/00000078

Vocabulary Word Henry’s law: the solubility of a gas in a liquid is proportional to the pressure of the gas above the liquid S1 = S2 solubility at pressure 1 P1 P2 solubility at pressure 2

Henry’s Law Is used to determine the solubility at different pressures