Upload
caren-hudson
View
229
Download
0
Tags:
Embed Size (px)
Citation preview
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
Solubilities of some solutes in water at varioustemperatures
Substance Solubility (g/100 g H2O)0oC 20oC 60oC 100oC
aluminum sulfate 31.2 36.4 59.2 89.0ammonium chloride 29.4 37.2 55.3 77.3barium hydroxide 1.67 3.89 20.94 -barium nitrate 4.95 9.02 20.4 34.4calcium hydroxide 0.189 0.173 0.121 0.076lead (II) chloride 0.67 1.00 1.94 3.20lithium sulfate 36.1 34.8 32.6 -potassium chloride 28.0 34.2 45.8 56.3potassium sulfate 7.4 11.1 18.2 24.1sodium chloride 35.7 35.9 37.1 39.2
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