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16 Cards in this Set
- Front
- Back
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Define a Solution Relationships between - Solute -Solvent - Solution |
Solution: - homogenous mix. of 2+ substanes combined into a single phase -Solute goes into a solvent: makes a solution |
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Define Solvation
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Solvation (hydration) - breaking bonds, electostatic interaction between solute and solvent (water normally solvent) -form new bonds between solute/solvent |
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Exothermic vs Endothermic Solvation
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Exothermic: new bonds created are stronger than initial bonds - Favored at lower temp. ex: gases in liquids Endothermic:: new bonds weaker than old bonds -req. energy to make them - High T( energy req.) favored - heat to dissolve ex: sugar in water if new interaction strength= strength original interactions, change in enthalpy= zero *called an ideal solution ∆H=0 - |
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Spontaneity of Dissolution
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*does not depend on just enthalpy - endothermic and exothermic can both be -∆G * + ∆G = non spontanoue -∆G= spontaneous *entropy increases after dissolution (always) depends on ∆H and ∆S --> ∆G= ∆H-T∆S |
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Solubility what is saturation? what is a dilute solution? What is a precipitate? |
solubility: max amount of substrate in a solvent @ a given temperature saturated: @ Keq w/ undissolved state - max amount of solute added Dilute: solute to solvent ratio is small -Precipitate (ex: glucose) will go to bottom - less dense, separate on top.. etc. |
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Aqueous Solution -Aqueous means water.. and water is polar or nonpolar? likes dissolve likes? DUH!! what are the solubility rules? - ammonium and what salts are always soluble? |
solubility rules.. -ammonium and group 1 salts are soluble - Nitrate, acetate are soluble salts - Cl, Br, I salts are soluble - |
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Concentration - what are the units Formula for % compostition Formula for Mole Fraction Formula Molarity |
Concentration: solute/solvent - can be by mass, M-molarity, Molality, or normality %composition by mass: Mass Solute/ Mass solution x100 Mole Fraction(X): Xa= Moles A/ Total moles all species Molarity(M): M= Moles solute/ Liters solution(tot.) |
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Concentration - Molality |
Molality: m = moles solute/ Kg of solvent * req. for B.P elevation and Freezing point depress. |
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Concentration -Normality |
Normality (N) is equal to number of equivalents of interest - OH-, H+, e-.... equivalent: equal to a mole of anything |
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Concentration -Dilution Formula - High concentration in solvent to low concentration in solvent - what could we add to a solution to make it less concentrated? |
Dilution High [A] -----> Low [A] by adding Solvent M1V1= M2V2 to Dilute to desired [M] |
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Solution Equilibria - is a solution saturated or unsaturated @Eq? @ Eq, is it @ high or low energy? Is it spont./nonspon. to move towards Eq, or away from Eq? |
Equilibria: Saturated (max solute) @ that T -Eq will be @ lowest Energy state
- Towards Eq: Spontaneous (-∆G) - Move away from Eq: Nonspont. +∆G |
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Solubility Product - general formula for Ksp - what is not includes in solubility product? - what affects Ksp of nongases vs gases? - what univerally affects equilibria? |
Ksp: Solubility Product Constant - @Eq for saturated solution of ionic compound Ksp= [A][B] if AB----> A+ + B- *do not include solids or pure liquids Ksp (just like Keq, Ka, Kb, kw) is T. dependent *if a gas is dissolved in liquid--- Ksp also dependent on Pressure For non gas solutes: Inc^ T ----- Inc^ Ksp Gas Solutes: Inc^T -----Decrease in Ksp Inc^ P ----- Inc^ Ksp |
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Ion Product(IP) how does IP compare to Ksp? when IP> or < or = to Ksp? What is the molarity called of a saturated substance called? a soluble salt gen. formula of MX will be for a soluble salt at MX2, the formula is.. MX3 formula |
Ion product same as Qc (reactant Quotient) - determine where system is reaching equilibria IP= [A][B] IP < Ksp rxn Unsaturated, rxn continue to dissolve IP > Ksp rxn supersaturated, rxn precipitates IP = Ksp rxn saturated and @ equilibrium Molarity solute in saturated solution - called molar solubility of that substance MX Formula: Ksp= X^2 x= molar solubilty ex: NaCl MX2: Ksp= 4x^3 x=molar solubility MX3: Ksp= 27x^3 *assume no common ion affect above^ |
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Common Ion Affect solubulity of a salt is considerably reduced when disolved in a solution already containing one of its constituents |
Common ion Effect - Solubility decreases if solution already has ions present in it - Ksp is unaffected - Rxn shifts to left <--- precipitate - molar solubility of solid will decrease ex: AgI into AgNO3 solution [Ag]= [AgNO3] already present if Kf (formation of stability constant) is Kf : if larger than Ksp -rate limiting step is 1st step - |
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Colligative Properties
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Colligative Properties- depend on [C] dissolved Vapor Pressure Depression - block evap @ surface.. not condensation -Raults Law: VP solution decreases as solute added Boiling Point Elevation - if VP solution decreases.. * need to increase Temp to reach atm * if VP decreases, BP increases Freezing Point Depression - freezing point decreases for every mole solute added - ex: salt lowers freezing point of water @winter time Osmotic Pressure - water "sucked" into solution that has higher solute concentration ex: Hydrostatic pressure vs Osmotic pressure@ capillaries |
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