test_3 - Solubility Products Consider the equilibrium that...

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Solubility Products Consider the equilibrium that exists in a saturated solution of BaSO4 in water: BaSO4(s) Ba2+ (aq) + SO42-(aq) The equilibrium constant for this expression is: Ksp= [Ba2+] [SO42-] The equilibrium constant, Ksp, is called the solubility product constant Ksp is NOT the same as solubility Solubility is generally expressed as the mass of solute dissolved in 1L (g/L) or 100 mL (g/mL) of solution, or in mol/L (M). Quantity present in some volume of saturated solution. Direct comparisons of the solubility of two salts on the basis of their Ksp values can only be made for salts having the same cation-to-anion ratio. Water insoluble compounds < 0.01 mol dissolved material/ L of solution; Extent to which an insoluble salt dissolves. Factors affecting solubility 1. The common-ion effect -If one of the ions in solution equilibrium is already dissolved in the solution, the equilibrium will shift to the left and the solubility of the salt will decrease BaSO4(s) Ba2+(aq) + SO42-(aq) 2. pH value If a substance has a basic anion , it will be more soluble in an acidic solution Substances with acidic cations are more soluble in basic solutions 3. Complex Ions Metal ions can act as Lewis acids and form complex ions with Lewis bases in the solvent. The formation of these complex ions increases the solubility of these salts. 4. Amphoterism Amphoteric metal oxides and hydroxides are soluble in strong acid or base , because they can act either as acids or bases Examples of such cations are: Al3+, Zn2+, and Sn2+ Will a precipitate form? In a solution: If Q = Ksp , the system is at equilibrium and the solution is saturated If Q < Ksp , more solid will dissolve until Q = Ksp. If Q > Ksp , the salt will precipitate until Q = Ksp One can use differences in solubilities of salts to separate ions in a mixture. First law of Thermodynamics Recall that energy cannot be created nor destroyed Therefore, the total energy of the universe is a constant . Energy can, however, be converted from one form to another or transferred from a system to the surroundings (exo or endo) or vice versa. Spontaneous Processes(IRREVERSIBLE) …those that can proceed w/o outside intervention Processes that are spontaneous at one temp may be non spontaneous at other temps Processes that are spontaneous in one direction are non spontaneous in the other direction The gas in vessel B will spontaneously effuse into vessel A, but once the gas is in both vessels, it will NOT spontaneously go back to the original state. Reversible Process The system changes in such a way that the system and surroundings can be put back in their original states by exactly reversing the process.

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2 graphs: Entropy Entropy (S) is a term coined by Rudolph Clausus in the 19 th century. Clausus was convinced of the sign if of the ratio of heat delivered and the temp at which it is delivered.
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test_3 - Solubility Products Consider the equilibrium that...

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