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65 Cards in this Set
- Front
- Back
Colligative properties determined by |
-Intermolecular interactions -Colligative properties is about how much SOLUTE you have |
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4 colligative properties |
1. Vapor pressure lowering 2. Boiling point elevation 3. Freezing point depression 4. Osmotic pressure |
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Ideal solution |
-Solution where there is no change in properties of components when mixed -Formed by mixing components with similar properties |
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Properties of ideal solution |
-No heat absorbed or released during mixing -Final volume = sum of volume of components -Properties are weighted averages of properties of pure components |
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Attractive forces in ideal gases |
-Ideal gases have no attractive forces -Molecules are so far apart they exert no intermolecular interaction on each other -Truly ideal gases have 0 volume |
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Attractive forces in ideal liquids |
-Ideal liquids have uniformity of attractive forces -Impossible to have NO attractive forces -Energy to break them up is equivalent A-A = B-B = A-B |
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Raoult's Law for Ideal Solutions |
PA = P°A × XA Ptotal = PA + PB = P°A × XA + P°B × XB P°= pure state X= mole fraction |
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Adhesive forces |
A-B interaction -Prevents or reduces vaporization -Solute-solvent |
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Cohesive forces |
A-A or B-B interaction -Solute-solute -Solvent-solvent |
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Cohesive forces > Adhesive forces |
-Positive deviation of Raoult's Law -Total pressure increases -A would rather react with itself than B so it can escape more easily BEYONCE ESCAPING - BOY BYE |
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Adhesive forces > Cohesive forces |
-Negative deviation of Raoult's Law -Total pressure decreases -A would rather react with B than itself so it is preventing evaporation AINT LETTING BEYONCE GO |
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Non-electrolytes |
-Do not ionize when dissolved -Do not conduct electrical current -Ex: sucrose, urea -Colligative properties are the same van't Hoff factor = 1 |
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Electrolytes |
-Forms ions in solution -Different colligative properties than non-electrolyte -Can be weak or strong van't Hoff factor = the # ions in solution after dissociation (ex: NaCl = 2) |
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van't Hoff i factor |
-Ratio of colligative properties of real solution to ideal solution Takes into account: - Behavior of ionic solutions - Actual # particles in solution after electrolyte dissolves -Activity coefficient --> electrolyte-solvent interaction Is theoretically = to ions in solution after dissociation |
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Boiling Point |
Temperature at which vapor pressure of liquid is = to external pressure of 760 mmHg |
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Boiling point elevation |
Boiling point of solution - boiling point of pure solvent ∆Tb = imKb |
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Ebullioscopic constant |
Kb = 0.51°C |
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Freezing point depression |
∆Tf = imKf |
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Cryoscopic constant |
Kf = 1.86°C |
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Beckmann Method |
Just an FYI - this is a way to determine freezing point depression |
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Two Vacuum Jacketed Flasks |
More accurate way to determine freezing point depression -One flask : pure liquid with pure solid solvent -Other : solution in equilibrium with pure solid solvent Measure temp separately & calculate difference |
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Semi-permeable membrane |
Allows passage of some solution components and not others |
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"Perfect" semi-permeable membrane |
Allows passage of solvent BUT NOT SOLUTE |
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"Real" semi-permeable membrane |
Allows passage of solvent AND some solutes Passage dictated by: size of solute & solubility of membrane |
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Osmosis |
Process by which solvent moves thru semi-permeable membrane from pure solvent (low concentration of solute) to higher [ ] solute *entropically driven |
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Thistle tube |
Water moves into bulb w/concentrated solution & is pushed up tube til equilibrium is reached π = pgh p= density g= gravity h= height of soln above surface |
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van't Hoff's Osmotic Pressure |
π = imRT R = 0.082 L*atm/mol*K note: KELVIN |
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"Push-Pull" Delivery System |
Tablet with tiny laser cut orifice -Drug mixed w/electrolyte inside semi-permeable membrane -Water flows in through membrane -Get swelling & polymer pushes drug out of orifice entropically driven |
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"L-OROS" Delivery System |
-Tablet or pump form -Drug in solution in flexible chamber surrounded by solid matrix of salt (electrolyte) surrounded by a semi-permeable membrane -Water flows in & pushes drug out -Pushing out AND dissolution entropically driven |
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RBC in 0.9% saline |
Isotonic -Cell is at equilibrium with saline -Water flows in & out at same rate -Cell remains normal & healthy |
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RBC in 2% saline |
Hypertonic -Water moves across membrane out of cell toward high NaCl [ ] -Cells shrink (crenate) -Water drives out of cell to restore equilibrium |
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RBC in 0.2% saline |
Hypotonic -Water moves into cell toward higher NaCl [ ] -Cells swell & potentially lyse (burst) -Water will go into cell to restore equilibrium |
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2% Boric acid & RBC |
-BA has same tonicity as 0.9% NaCl -In RBC will move from outside cell, into cell *BUT!* BA will bring MORE H2O along with it --> starts swelling |
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Tonicity of IV Fluids |
Normal = 280 - 290 mOsm/L Fluid with osmotic pressure > 550 should be infused SLOWLY for safety |
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Excess infusion of hypotonic IV fluids results in... |
-Hemolysis of RBC's -Edema -Convulsions |
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Excess infusion of hypertonic IV fluids results in... |
-Dehydration -Hypoglycemia -Loss of electrolytes -Coma -Osmotic diuresis |
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Factors for toxicity in IV medications |
-Derivation from tonicity -# molecules in preparation -Location of injection (ex: IV versus elsewhere) -Volume & rate of injection |
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Osmolarity of physiological fluids |
280-290 mosmol/kg serum, tears, saliva |
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Enteral nutrition products |
For patients with trauma & need the fluid they cannot eat -hypertonic |
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Results of giving nutritional product given IV: |
↓ blood pressure Cardiac irregularities Pulmonary edema Cerebral hemorrhage |
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Route of administration for nutrition products |
-Oral -Gastric tube -Direct instillation (port)- jejunum/stomach |
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Hypertonicity in enteral meals |
-Hypertonic & hyperosmotic due presence of smaller molecules (AA, electrolytes) than what is normally in food |
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Factors that impact tonicity of hypertonicity in enteral meals (from most to least) |
"Every cat sleeps on fluffy pillows forever" 1. Electrolytes 2. Complex sugars 3. Starches 4. Organic molecules 5. Flavorings/coloring 6. Proteins 7. Fats |
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Imbalance of osmotic effect can lead to... |
-Cramping -Nausea -Vomiting -Shock **should be given slowly** |
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Oral Rehydration Therapy (ORT) |
-Used in cases of severe fluid loss -We talking severe vomiting/diarrhea, ok ok -Focuses on glucose/Na+ transported in intestine (assist in bringing in H2O) -Actually isn't all that great. Intestine getting rehydrated, but blood EVEN more dehydrated -More dehydration & risk of death |
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Food-based ORT |
-Chicken noodle soup to the rescue! -Complex molecules in soup (protein, starch) have same effect as 1 single glucose molecule -Enhance nutrient induced Na+ transport -Rapid uptake at surface - avoids osmotic penalty -Water & ions returned to blood quickly -Extent & duration of diarrhea reduced! |
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Isosmotic does not equal isotonic |
Boric Acid in the eyeballs - take home message: -A solution containing a qty of drug calculated to be isoosmotic, is isotonic ONLY when the membrane under consideration is IMPERMEABLE to the solute & PERMEABLE to the solvent |
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Sodium chloride equivalent values (E) |
-Kinda like conversion factor = 0.9 -By convention, 1 g of any drug that can replace the entire amt of NaCl in the solution will have a NaCl "E value" of 0.9 |
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How to prepare sodium equivalent (E) |
Step 1: From volume of solution, calculate total amt of NaCl needed to be isotonic Step 2: Convert amt of drug/solute to equivalent in NaCl Step 3. Subtract the difference between 1 & 2 |
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Partition coefficient |
-Equilibrium constant for partitioning process -Some fraction will go into oil phase, some into water Ko/w = [drug]oil / [drug]water |
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Partitioning Process |
-Involves 2 immiscible liquids (immiscible to each other) -Rate of the equilibrium [ ] of solute in solvent A & its equilibrium [ ] in solvent B Ex of liquids: water (always), octanol, amyl alcohol, chloroform, CCl4 |
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Thermodynamic forces involved in partitioning? |
-Disruption of interaction of solute with water solvent -Formation of bond between solute with oil |
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Oil to Water partition coefficient |
-The standard nomenclature K o/w K eq = [A] oil / [A] water Warning: You can write the reverse but be careful of its meaning! |
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What is an emulsion? Give 2 examples. |
The drug is trapped in a droplet & distributed throughout the preparation. Ex. Oil drops in water --> Vinaigrette dressing, lotions Ex. Water drops in oil --> mayonnaise, creams |
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Two benefits of emulsions |
-Masks taste -Improve absorption rate |
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Yalkowsky and Valvani equation |
logS = -logK - 1.11 ((∆Sf (mp-25)) / 1364) + 0.54 S= aqueous solubility (mol/L) K= oil to water part coeff (Ko/w) ∆Sf= molar entropy of fusion mp= melting point (°C) |
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∆Sf for non-rigid molecules with more than 5 non-hydrogen atoms
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13.5 + 2.5(n-5) n= # of non-hydrogen atoms |
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How does benzoic acid act as preservative? |
-Unionized form of benzoic acid can cross bacterial walls and acidify the bacteria (not harmful to humans) |
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Distribution of benzoic acid among oil/water phase depends on.... (3 things) |
Ko/w Ka q Use equation: C total = (K o/w * q + 1 + (Ka/[H+]) [HA]w |
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Drug Action & Partition coefficient |
↑Ko/w = ↑ drug absorption
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Vaseline & mineral oil are examples of....? |
-When water solubility is so low that a significant concentration in water cannot be achieved, absorption may be negligible -EVEN though there was a favorable partition coefficient |
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Physical Barriers/Membranes |
-Skin 2-3mm thick, virtually water proof. Need fairly HIGH partition coefficient -Buccal 40-50 cell layers -Sublingual 100-200 um -Intestinal not as complex |
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Partition coefficient of drug depends on TWO Factors |
1. The polarity of the drug 2. The size of the drug (more lipophilic = higher partition coefficient) |
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Concern of drug partitioning into plastics |
-Higher K o/w suggests drug will ESCAPE into or absorb into plastic tubing -Reduces drug efficacy -Result: you deliver unusually high doses to achieve efficacy |
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Rule of thumb for drug partitioning/IV plastic |
↑Ko/w ↑ chances of leaching to PVC bags/tubing |