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9 Cards in this Set
- Front
- Back
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Ksp
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solubility product
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saturated
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solution is saturated when the dissolution rxn is at equilibrium and no more solid appears to dissolve
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B/c amount of tetraborate is related to ____, we can...
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-related to the amount of OH-
-if we can determine the number of OH- ions in solution, we know the amount of tetraborate ions -use titration to count # of OH- ions in solution (add H+ ions through strong acid HCl until we've added 1 H+ for each OH- present -the point where all the OH- is used up (converted to water) is the titration's eq. pt. -to find this, we will use an acid/base indicator that will change color when the OH- ions are gone -at this point, the # of OH- ions initially present = # H+ ions we've added -find # of H+ ions added from volume and concentration of the acid used |
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Once we know tetraborate concentration...
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we can calculate the Ksp for borax using the equilibrium expression for the dissolution
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By performing titrations of borax solutions at different temperatures...
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we can measure the temp dependence of Ksp and find delta G, deltaH, deltaS (naught)
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deltaG (naught) equations
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dG = dH - TdS
(d=delta) (naught on G, H, S) dG=-RTln(K) |
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ln(K) equation
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ln(K) = -(dH/R)(1/T) + dS/R
y=mx+b (naught on H and S) |
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General info about this experiment
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-determine solubility product Ksp for Borax at different temperatures
-create a Van't Hoff plot to calculate the thermodynamic parameters deltaH, deltaS and delta G (naught) |
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Lab procedure
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-each group sets up a saturated borax solution (borax, distilled water) at their assigned temperature (cold solution in ice bath, one at room temp, third warmed on a hot plate)
-let borax solution temp be stable for several min, and solid borax must be present (demonstrating equilibrium) -get 4 250 mL flasks, put 5 mL borax solution into each one, add distilled water until reaches 250 mL mark -add 4 drops of bromocresol green indicator --> solution should become a light blue color -do titrations |
