PHA 325 Principles of Pharmacy Final Exam | Questions And Verified Answers |

PHA 325 Principles of Pharmacy Final Exam | Questions And Verified Answers | Qualitatively, solubility is the... - Answers-spontaneous interaction of two or more substances to form a homogenous molecular dispersion (i.e. solution) .Quantitatively, solubility is the... - Answers-concentration of a solute in a saturated solution at a given temperature ._____________________ is the principal factor that influences solubility - Answers-Temperature .point of chemical kinetics - Answers-stability of drug over time under influence of variety of conditions, predict shelf life and storage for degradation .Solubility is a(n) _____________ physical property of a substance - Answers-intrinsic .When the solute and the solvent come together, energy is ________________. The overall exchange of energy can be positive or negative and is called the... - Answers-released; heat of solution .Endothermic: Heat of Solution is _________________ - Answers-negative .Exothermic: Heat of Solution is _________________ - Answers-positive .chemical kinetics - Answers-mechanism chemical process gets to final state from initial state and rate .Polar - Answers-solvent molecules have large dipole moments and high dielectric constants (e.g. water) .Non-Polar - Answers-solvent molecules have low dipole moments and small dielectric constants (e.g. oils) .__________________ properties relate to the ability to store charge which influences how a substance interacts with solvents - Answers-Dielectric .___________________ bonding is important to solubility as the formation of these intermolecular bonds stabilize the molecule in solution - Answers-Hydrogen .Water has a __________ dielectric constant - Answers-high .Intrinsic solubility of a non-electrolyte in water (S0) equals its _________________ concentration in solution - Answers-maximum .Not every collision leads to a product, why? - Answers-The successful collisions must have enough energy, also known as activation energy, at the moment of impact to break the preexisting bonds and form all new bonds .Weak Acid Equilibrium Constant - Answers-or pH = pKa + log((S-S0)/S0) .Weak Base Equilibrium Constant - Answers-or pH = pKa + log(S0/(S-S0)) .What pH will free phenobarbital begin to separate from a solution having an initial concentration of 1 g of sodium phenobarbital per 100 mL water at 25ºC? (S0 = 0.005 M, pKa = 7.41, and MW = 254) - Answers-Initial molar concentration = 10 (g/L) / 254 = 0.039 M pH = 7.41 + log ](0.039 - 0.005)/0.005] = 8.24 .What is the minimum pH required for the complete solubility of the drug in a stock solution containing 6 g of phenobarbital sodium in 100 mL of a 30% by volume alcoholic solution? (S0 = 0.028 M, pKa = 7.92, and MW = 254) - Answers-Initial molar concentration = 60 (g/L) / 254 = 0.236 M pH = 7.92 + log [(0.236 - 0.028)/0.028] = 8.79 .A new drug is a sodium salt of a carboxylic acid. It has a MW of 150 and pKa of 5 with an intrinsic solubility of 0.002 M. what is the maximum concentration of the drug that can be dissolved in a buffer at pH = 6? - Answers-S = S0 (1 + 10^(pH-pKa) S = 0.002 (1 + 10^1) S = 0.022 M .What could be reasons that the use of pH adjustment to increase solubility may not be appropriate for a drug? - Answers- .Strong acids and bases and their salts are _______________ in water - Answers-soluble .Weak acids and bases with ________ molecular weight are often not soluble in water - Answers-high .What is the minimum pH required for the complete solubility of the drug in a stock solution containing 1 g of phenobarbital sodium in 100 mL of a 30% by volume alcoholic solution? (S0 = 0.028 M, pKa = 7.92, and MW = 254) - Answers-Initial molar concentration = 10 (g/L) / 254 = 0.039 M pH = 7.92 + log [(0.039 - 0.028)/0.028] = 7.51 (in 30% alcohol solvent) pH = 7.41 + log[(0.039 - 0.005)/0.005] = 8.24 (in water) .Solubility of a non-electrolyte in water is increased or decreased by the addition of an ________________________. - Answers-electrolyte (i.e. salt) .basis for understanding chemical kinetics - Answers-chemical degradation and time dependence .collision theory - Answers-reaction when atom collides with another=transfer of energy .transfer of energy in collision theory - Answers-increase kinetic energy--increase in velocity or disrupt bonds in molecule .when are collisions more likely to happen/more frequent? - Answers-higher concentration .rate of reaction (2) - Answers-proportional to # of collisions velocity that reactant undergoes chemical change .experimental rate of reaction - Answers-follow change in concentration as function of time of reactants or measure concentration of appearance of product .law of mass action - Answers-the rate of a chemical reaction, at a given temperature, is proportional to the molar concentration of the reactants raised to a power equal to the number of molecules of each reactant .The _______ _______________ does not change so long the conditions (e.g. temperature, solvent, the reacting species) are stable - Answers-rate constant .k - Answers-reaction rate constant independent of reactants concentration at a given temperature .order of reaction - Answers-sum of exponents of concentration terms in rate equation .elementary reaction - Answers-each step in a reaction with several steps .molecularity - Answers-number of atoms/molecules reacting in a elementary reaction step .unimolecular - Answers-1 molecule reacting in elementary step .bimolecular - Answers-2 molecules reacting in elementary step .half life (t1/2) - Answers-time required for 1/2 material to disappear or concentration to reach 50% of initial value .shelf life (t90) - Answers-time required for 10% of material to disappear or concentration to reach 90% of initial at storage conditions, how expiration date determined .t₉₀ = - Answers-0.105/k .zero order reaction - Answers-rate of reaction constant and independent of concentration of reactant .Apparent zero order rate constant = t₉₀ = - Answers-1. (first order rate constant)x(drug solubility) 2. ((0.1)(how much the script calls for))/(Apparent zero order rate constant) .first order reaction - Answers-rate of reaction proportional to concentration of ONE of reactants .t½ = - Answers-0.693/k .2nd order reaction - Answers-rate of reaction proportional to concentration of 2 reactants .apparent order reaction - Answers-pseudo order reaction rate of reaction independent of concentration of 1 or more reactants over a wide range of concentrations .conditions for apparent order reactions - Answers-1. 1 or more reactants enter in great excess 2. 1 reactant is catalyst 3. 1+ reactant constantly replenished .Suspensions generally show... - Answers-apparent zero-order reactions .determine order graphically - Answers-Straight line 1. concentration vs time=0 order 2. ln(concentration vs time=1st order 3. ln (C/D) vs time=2nd order .ln(concentration) vs time results in a straight line - Answers-First Order .Concentration vs time results in a straight line - Answers-Zero Order .If ln(C/D) vs time results in a straight line - Answers-Second Order .complex reactions - Answers-2+ elementary steps 1. reversible 2. parallel/side reactions 3. consecutive/series .k = - Answers-((ln(initial)-ln(final))/(time) .Reversible Reaction - Answers-The simplest reaction in which both the forward and reverse reactions are first order processes .Parallel or Side Reaction - Answers-reaction in which the reactant undergoes simultaneous reactions through different pathways forming multiple products .Consecutive or Series Reaction - Answers-the reactant undergoes decay in a series of reactions forming one or more intermediates before reaching the final product .The half-life of degradation for a drug undergoing a first order reaction is 4 years. What would be the estimated expiration date? - Answers-t1/2 = 4 years = 0.693/k k = (0.693/4) = 0.173 years^-1 t90 = 0.105/k = (0.105/0.173) = 0.61 years .The stability of a drug was studied at pH 6. The starting concentration of the drug is 10 mg/mL. After 50 days, the concentration in the solution is 6.5 mg/mL. Assuming this is a first-order reaction, calculate the rate constant and half-life of the drug in this solution. - Answers-k = (ln(10)-ln(6.5))/50