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Solubility. Honors Chemistry Mrs. Jacobus. Components of a Solution. Solute is the substance being dissolved – powder Solvent is the dissolving agent – water . Solute. Dissolve. Solvent. Solubility. The amount of solute that will dissolve in a given amount of solvent.
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Solubility Honors Chemistry Mrs. Jacobus
Components of a Solution • Solute is the substance being dissolved – powder • Solvent is the dissolving agent – water Solute Dissolve Solvent
Solubility The amount of solute that will dissolve in a given amount of solvent. Soluble vs. insoluble • May vary with solvent • “Like dissolves like”
Polar and Nonpolar • A polar bond is a covalent bond between two atoms where the electrons forming the bond are unequally distributed • A nonpolar bond is a covalent bond between two atoms where the electrons forming the bond are equally distributed Nonpolar Molecule (CH4) Polar Molecule (H2O)
“Like dissolves like” Two substances with similar intermolecular forces (force between two molecules) are likely to be soluble in each other. • non-polar molecules are soluble in non-polar solvents • CCl4 in C6H6 • polar molecules are soluble in polar solvents • C2H5OH in H2O • ionic compounds are more soluble in polar solvents • NaCl in H2O or NH3 (l) 12.2
Factors Affecting Solubility • Temperature • Pressure Solubility is the amount of solute that will dissolve in a given amount of solvent at a given temperature or pressure.
Factors Affecting the Rate of Dissolution • Stirring • Temperature • Particle size/Surface area
A saturated solution contains the maximum amount of a solute that will dissolve in a given solvent at a specific temperature. An unsaturated solution contains less solute than the solvent has the capacity to dissolve at a specific temperature. A supersaturated solution contains more solute than is present in a saturated solution at a specific temperature. Sodium acetate crystals rapidly form when a seed crystal is added to a supersaturated solution of sodium acetate. 12.1
solubility increases with increasing temperature solubility decreases with increasing temperature Temperature and Solubility Solid solubility and temperature 12.4
Saturated, Unsaturated & Supersaturated Ex.1) If 10.0 g of KCl is dissolved in 100.0 g of water at 20.0oC, then would the solution be described as unsaturated, saturated, or supersaturated? ________________________________________. Ex.2) If 10.0 g of KClO3 is stirred into 100.0 g of water at 20.0oC, then would the solution be described as unsaturated, saturated, or supersaturated? ________________________________________. Ex.3) If 10.0 g of KClO3 is dissolved in 100.0 g of water at 20.0oC, then would the solution be described as unsaturated, saturated, or supersaturated? ________________________________________. unsaturated saturated with about 1 g of undissolved KClO3 supersaturated
Saturated, Unsaturated & Supersaturated Ex.4) If 100.0 g of KI is stirred into 100.0 g of water at 20.0oC, then would the solution be described as unsaturated, saturated, or supersaturated? ______________________________________ Ex.5) If 100.0 g of KNO3 is stirred into 100.0 g of water at 60.0oC, then would the solution be described as unsaturated, saturated, or supersaturated? ______________________________________ Ex.6) How many grams of KNO3 will exactly saturate 200.0 g of H2O at 20.0oC? ______________ g unsaturated unsaturated ≈70
Temperature and Solubility O2gas solubility and temperature solubility usually decreases with increasing temperature 12.4
Watch the following video: http://www.youtube.com/watch?v=XSGvy2FPfCw What kind of a solution is it?
Need more help? • http://www.wwnorton.com/college/chemistry/gilbert2/tutorials/interface.asp?chapter=chapter_04&folder=saturated_solutions • Norton tutorial on solubility • http://www.youtube.com/watch?v=zjIVJh4JLNo&edufilter=d3ViuWqXvxQy1rRgssBz8Q • Basic solubility • http://www.youtube.com/watch?v=4VltXjR64SU&edufilter=d3ViuWqXvxQy1rRgssBz8Q • Molarity vs. Molality
moles of solute liters of solution moles of solute m = mass of solvent (kg) M = Concentration Units Continued Molarity(M) Molality(m) 12.3
moles of A XA = sum of moles of all components x 100% mass of solute x 100% = mass of solution mass of solute mass of solute + mass of solvent Concentration Units The concentration of a solution is the amount of solute present in a given quantity of solvent or solution. Percent by Mass % by mass = Mole Fraction(X) 12.3
moles of solute moles of solute m= m= moles of solute M = mass of solvent (kg) mass of solvent (kg) liters of solution 5.86 moles C2H5OH = 0.657 kg solvent What is the molality of a 5.86 M ethanol (C2H5OH) solution whose density is 0.927 g/mL? • Assume 1 L of solution: • 5.86 moles ethanol = 270 g ethanol • 927 g of solution (1000 mL x 0.927 g/mL) mass of solvent = mass of solution – mass of solute = 927 g – 270 g = 657 g = 0.657 kg = 8.92 m 12.3