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PS400 Exam 1
PharmSci 400 Exam 1
| Question | Answer |
|---|---|
| True or False: at constant temp, the change of enthalpy is head absorbed or released by the system | false |
| true or false, can a process occur spontaneously even though it requires heat absorption | true |
| true or false, osmotic pressure of electrolyte solutions depends on the degree of solute dissociation | true |
| What is entropy | the amount of disorder in a system (number of microscopic states) |
| what letter represents entropy | delta S |
| what is enthalpy | overall heat in a reaction system represented by delta H |
| what is work | mechanical energy transferred between two systems represented by W |
| what is heat | thermal energy transferred between two systems represented by Q |
| what is heat capacity | how much heat must be added to a substance to raise its temp by 1 degree Celsius |
| what is gibbs free energy | defines if a reaction will be spontaneous |
| what sign must delta G be for it to be spontaneous | negative |
| what happens to enthalpy if pressure is constant | it is equal to Q (heat) because work would be less than 0 due to an expansion which causes a decrease in energy |
| in a closed, adiabatic system what is energy equal to | work |
| in an isolate, adiabatic system what is energy equal to | zero |
| in a closed system with no work transfer what is energy equal to | heat |
| what are the three laws of thermodynamics | - conservation of energy - entropy of the universe increases - entropy of a perfect crystal at absolute zero temp is zero |
| when is Raoult's law used | only for ideal solutions |
| what is an ideal solution | - interactions are the same between all the molecules of the solution - the molecules are usually similar to each other |
| What is the enthalpy of mixing for a ideal solution | zero --> heat from making new bonds between A and B are equal to the heat from breaking bonds from molecules |
| what is colligative properties | Properties that depend on the relative proportion of solute and solvent molecules rather than their identities |
| what happens to vapor pressure when adding a nonvolatile solute to a volatile solvent | decreases |
| what is molality (m) | moles of solute per 1000g of solvent |
| what is Molarity (M) | moles of solute per 1 L of solution |
| what two properties are not colligative | solubility, and viscosity |
| what is osmosis | diffusion of water through a semipermeable membrane from a low concentration f solute to a high concentration of solute |
| what are electrolytes | Substances that can dissociate to become ions in solution and acquire the capacity to conduct electricity |
| what are strong electrolytes | Almost completely dissociate into ions in solutions; often ionic solids or strong acids/bases |
| what are weak electrolytes | - Do not completely dissociate into ions in solution - often weak acids/bases |
| what are non electrolytes | - Do not dissociate or conduct electricity in solution - often non acids/bases like sucrose |
| what is the freezing point of human blood | -0.52 degrees celsius |
| what is the NaCl concentration in the body | 0.9% |
| what happens to cells in a hypertonic solution | they will lose volume due to movement of water out of the cell |
| what happens to cells in a hypotonic solution | water moves in causing the cell to burst |
| what does boric acid do in a solution | able to freely pass thru semi permeable membranes and will not contribute to osmotic pressure bc its concentration eventually reaches equilibrium |
| why is a buffer important | - helps control pH of a liquid dosage form - maintains minimal degradation of the drug at the select pH where the drug is most stable - improve the solubility of a water insoluble drug in certain cases |
| what is a buffer capacity | Describes the resistance of a buffer to changes in pH |
| what happens to the buffer capacity when you increase the buffer concentraiton | it increases |
| what happens to the pKa when the temperature coefficient dpKa/dt is greater than 0 | there's a pos correlation → increase temp = increase pKa |
| what happens to the pKa when the temperature coefficient dpKa/dt is less than 0 | there's a neg correlation → increase Temp = decrease pKa |
| what is the dispersed phase in an emulsion | liquid broken into small droplets |
| what is the continuous phase in an emulsion | liquid surrounding those droplets |
| what percentage of emulsifier is needed to prolong stability | 1-5% but closer to 5 |
| what are the most common emulsifiers | surfactants |
| what would happen if there was not an emulsifier | emulsion would spontaneously coalesce/phase separate |
| what does an emulsion do | Increases the solubility of water insoluble drugs, allowing higher doses |
| what is a con to emulsions | not suitable for autoclaving, potential of microbial contamination if not handled properly, harder to preserve |
| what is the appearance when the particle size of droplets is greater than 1µm | white |
| what is the appearance when the particle size of droplets is between 0.1 and 1 | blue-white |
| what is the appearance when the particle size of droplets is between 0.05-0.1 | semi transparent |
| what is the appearance when the particle size of droplets is less than 0.05 | transparent |
| what causes the appearance to be the way it is | - due to differences in refractive index of the two phases and the scattering of light which is dependent on particle size - Bigger particle size scatters more light making it appear white to us |
| amphophilic compounds forms what | oriented monolayer at phase interfaces where the hydrophilic grp dissolves in aqueous phase and lipophilic group dissolves in oil phase |
| why should you not use anionic and cationic surfactants together | they will become attracted to one another |
| why is a charged surfactant not convenient sometimes | they're sensitive to pH changes while non-ionic surfactants are not |
| what is a benefit of charged surfactants | charge repulsions between droplets increase the stability of the emulsions compared to non-ionic surfactants |
| what is interfacial tension | Cohesive force causing each liquid to resist breaking up into smaller particles |
| what does using an emulsifier do to interfacial tension | lowers it |
| what is the critical micellization concentration | represents point at which surface is saturated, and surfactants start to form micelles |
| an increase in length of hydrocarbons results in a ________ in CMC | decrease |
| Surfactants with higher HLB values (>8) are favorable or unfavorable for formation of o/w emulsions | favorable |
| Those with a lower HLB value (3-6) are more suitable for the formation of what kind of emulsions | w/o |
| what requirements are needed for surfactants for emulsions to be most stable | - need to provide the lowest interfacial tension between oil and water phase - when their HLV value is close to the required HLV value of the oil phase |
Created by:
rach6774