Chemical Kinetics and Stability: Chapter 14 Lecture 1

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Questions and Answers

Match the following terms with their definitions:

Stability = Important in determining shelf life and expiration date Decomposition = Process of breaking down drug products pH = Level at which thiamine hydrochloride is most stable Buffered vehicle = Prevents degradation of drug products

Match the following factors with their effect on stability:

Temperature = Affects the stability of drug products Humidity = Can impact the stability of thiamine hydrochloride Light = Influences the stability of drug products pH level = Determines the stability of thiamine hydrochloride

Match the following terms with their Arabic translation:

Stability = استقرار Decomposition = تحلل pH = درجة الحموضة Buffered vehicle = السيارة المخزنة

Match the following statements with the correct drug product behavior:

Thiamine hydrochloride stable at pH of 2 to 3 = Most stable within a specific pH range Thiamine hydrochloride unstable above pH 6 = Becomes unstable at higher pH levels Select buffered vehicle for preparation = Choose a vehicle that prevents degradation during preparation Stability affected by temperature, humidity, and light = External factors influence the stability of drug products Signup and view all the answers

Match the following terms with their definitions:

Molecularity = Number of molecules, atoms, or ions reacting in an elementary process Specific Rate Constant = Constant appearing in the rate law associated with a single-step reaction Half-life = Time required for one-half of the material to disappear Shelf-life = Time required for 10% of the material to disappear Signup and view all the answers

Match the following terms with their meanings:

Rates, Order, and Molecularity of Reactions = Classification of reactions into unimolecular, bimolecular, and termolecular Termolecular = A reaction involving three molecules, atoms, or ions Unimolecular = A reaction involving one molecule, atom, or ion Bimolecular = A reaction involving two molecules, atoms, or ions Signup and view all the answers

Match the following concepts with their descriptions:

Chemical Kinetics = Study of rates of chemical processes and reaction mechanisms Stability = Ability of a substance to remain unchanged or maintain a specific form under specified conditions Zero-Order Reactions = Reactions where the loss in color of a dye follows a zero-order rate Kinetic Study = Investigation into the rate of change of concentration over time Signup and view all the answers

Match the following equations with their meanings:

Rate = K[Reactant]^a = Representation of the rate law where K is the rate constant and 'a' is the order of reaction dc/dt = K[Reactant] = Expression for the rate, velocity, or speed of a reaction 2NO -> N2O2 (Fast) N2O2 + O2 -> 2NO2 (Slow) = Example revealing real detail mechanism by kinetic study Br H + I 2 -> 2HI 2NO2 -> 2NO + O2 = Example showing molecularity classification Signup and view all the answers

Match the following time-related terms with their definitions:

Half-life = Time required for one-half of the material to disappear Shelf-life = Time required for 10% of the material to disappear Life-assumed time = Time at which 10% of the material has decreased to 90% of its original concentration Infinitesimal time interval dt = Very small time period over which concentration changes in a reaction Signup and view all the answers

Match the following terms related to reactions with their explanations:

Elementary Process = Individual step in a reaction mechanism involving a small number of molecules or atoms Order of Reaction = Exponent 'a' in the rate law equation representing how concentration affects the rate of reaction Reaction Mechanism = Sequence of elementary steps that make up an overall chemical reaction Rate Constant = Constant value that relates the rate of a reaction to the concentration of reactants Signup and view all the answers

Match the following concepts with their interpretations:

Concentration Effects = Effects on reaction rates due to changes in reactant concentrations Fundamentals = 'ABC' basics that are foundational to understanding chemical kinetics Kinetic Study Findings = Discoveries related to how rates change over time in chemical reactions Stability in Pharmacy Preparations = 'ABC' basics that are foundational to understanding chemical kinetics Signup and view all the answers

Match the following terms with their roles:

Chemical Kinetics Applications in Pharmacy = Result in production of more-stable drug preparations Real Detail Mechanism by Kinetic Study = Revealed by investigating rates and mechanisms in reactions Molecularity Classification Example = 'Br H + I 2 -> 2HI' showing classification into unimolecular and bimolecular reactions Specific Rate Constant Definition Example = 'Rate = K[Reactant]^a' representing rate law for single-step reactions Signup and view all the answers

Match the following definitions with their corresponding concepts:

Classifying Reactions by Molecularity = 'Unimolecular', 'Bimolecular', and 'Termolecular' classification based on number of reacting species Zero-Order Reactions Study Findings = 'Garrett found that loss in color of dye follows zero-order rate' discovery Half-life Calculation Importance = 'Time required for half material to disappear' crucial for understanding reaction kinetics over time periods Shelf-life Implications on Concentration Changes = 'Time required for 10% material to disappear' helps assess stability based on concentration decrease Signup and view all the answers

Match the following terms with their effects:

Chemical Kinetics Applications in Pharmacy Impact on Drug Preparations = 'More-stable drug preparations' result from utilizing chemical kinetics in pharmacy applications Real Detail Mechanism Discovery Impact on Reaction Understanding = 'Real detail mechanism revealed by kinetic study' enhances comprehension about reaction rates and mechanisms Molecularity Classification Example Impact on Reaction Categorization = 'Br H + I 2 -> 2HI' example aids in categorizing reactions based on number of reacting species Specific Rate Constant Definition Example Impact on Rate Law Understanding = 'Rate = K[Reactant]^a' example clarifies how rate constant and order affect reaction rates Signup and view all the answers

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Study Notes

Chemical Kinetics and Pharmacy

Applications of chemical kinetics in pharmacy result in the production of more-stable drug preparations.
Chemical kinetics is used to study the rates, order, and molecularity of reactions.

Molecularity

Molecularity is the number of molecules, atoms, or ions reacting in an elementary process.
Molecularity can classify a reaction as unimolecular, bimolecular, or termolecular.
However, molecularity cannot give complete details about the order of a reaction, especially for multistep reactions.

Order of Reaction

The order of a reaction is given by the exponent 'a' in the rate law equation: Rate = k [Reactant]^a.
The rate constant 'k' is specific to each reaction.
The half-life is the time required for one-half of the material to disappear.
The shelf-life is the time required for 10% of the material to disappear.

Zero-Order Reactions

A zero-order reaction is a reaction where the rate of reaction is independent of the concentration of the reactant.
The rate expression for a zero-order reaction is: Rate = k.

Stability of Drug Products

The stability of drug products with time is crucial in determining their shelf life and expiration date.
Factors affecting stability include temperature, humidity, and light.
The pH of a solution can affect the stability of a drug product, e.g., thiamine hydrochloride is most stable at a pH of 2 to 3.
Pharmacists should select a buffered vehicle that prevents degradation of the drug product.