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What is chemical kinetics?
The study of rates of chemical processes.
What is the significance of a drug in a pharmaceutical product?
A drug undergoes chemical changes with time and may react with the environment.
Which factors can affect the rate of a chemical reaction? (Select all that apply)
What are ineffective collisions?
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What is required for a collision to be effective?
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What does activation energy (Ea) refer to?
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How is reaction rate defined?
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Reaction rate is measured in ___mol/ml/s.
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The average rate of reaction involves the ___ of change of concentration of a reactant.
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The reaction is first order with respect to the organic molecule and that's all, indicating that the slow step involves the ______.
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The hydroxide ion plays a key role by approaching a carbon atom with a slight positive charge and resulting in the bromine being ______.
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To determine the order of a reaction, one must conduct ______ rather than deducing it from equations.
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Molecularity refers to the number of ______ involved in a step of the reaction mechanism.
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In one case, the reaction is first order with respect to both the organic compound and the hydroxide ______.
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Understanding the difference between molecularity and the ______ of a reaction is crucial for applying kinetics correctly.
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The collision between the hydroxide ion and the organic molecule is described as a ______ event.
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The mechanisms of reactions can be inferred from knowing the ______ of the reaction.
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The differential rate law for the reaction A → Product is Rate = -d[A]/dt = k [A]^______
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The integral rate law is expressed as ln[A]t = ln[A]o - k______
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When plotting ln Ct versus time, the slope of the resulting straight line equals ______
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The rate law is expressed as Rate = k [S2O82-]^[x] [I-]^[y], where x = ______ and y = ______.
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For zero order reaction, k = (Co - Ct) / ______
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When the concentration of [I-] doubles, the rate ______ in experiments 1 and 2.
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The half-life of a first-order reaction is equal to ln2 divided by ______
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According to the isolation method, a minimum of a ______-fold stoichiometric excess is necessary for reliable determination of reaction order.
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If a straight line is obtained by plotting ______ versus time, the reaction is zero order.
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In first-order kinetics, the unit of the rate constant k is ______
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In the equation k = 2.2 x 10-4 M/s divided by the product of concentrations, 0.08 M and 0.034 M, k equals ______.
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To convert the logarithmic form, the equation log Ct = log Co – kt/2.303 can be simplified to Ct = Co e^______
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For first order reactions, k can be calculated using ln(C0) - ln(Ct) / ______
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In the case of second order reactions, the half-life (t1/2) is ______ proportional to Co.
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The relationship ln [C0/½ C0] = k t______ shows how the concentration changes over time.
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The rate expression determined from the experiments is: rate = k [S2O82-]^[1] [I-]^[1], represented in the format: Rate = k ______ ______.
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If the concentration of [S2O82-] is doubled, the rate ______ in experiment 2 and 3.
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In zero order reactions, the rate law is expressed as rate = ______.
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When log Ct is plotted versus time, the slope of the obtained straight line equals ______/2.303.
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For first order reactions, the relationship is given by the formula ln(Ct) = ln(C0) - ______t.
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In the reaction A + B → product, when [B] is much greater than [A], the concentration of [B] is regarded as ______.
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If t1/2 is constant, the reaction is said to be of ______ order.
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The rate constant k for the given reaction is calculated to be ______.
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The rate law for second order reactions is expressed as rate = k______2, where ______ represents the concentration of the reactant.
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The rate of reaction is represented by the change in concentration of the reactants over the change in _____.
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In the reaction aA + bB → cC + dD, the symbols a, b, c, and d are known as ____ coefficients.
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For the reaction H2 + Br2 → 2 HBr, if the change in Br2 is -0.001 mol/L, then d[H2]/dt is equal to ____ mol L-1 sec-1.
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The rate of the given reaction can also be expressed as v = ____ mol L-1 sec-1.
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In reversible reactions, the concentration change of reactants or products depends on the difference in the rates of the ____ and reverse reactions.
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Rate laws must be determined experimentally as they cannot be predicted from the overall ____ equation.
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In the study of kinetics, the two forms of rate laws are the differential rate law and the ____ rate law.
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As a reaction progresses, the initial rate of reaction is typically large, but eventually decreases to ____ as the reaction completes.
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Study Notes
Reaction Kinetics
- The study of chemical reaction rates and factors that influence them.
- Investigates reaction mechanisms and transition states.
- Reaction rate is influenced by factors such as:
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Nature of reactants:
- Some react faster than others
- Example: Oxidation of ferrous ion by KMNO4 is faster than oxidation of oxalate ion by the same reagent.
- Temperature: Higher temperature, faster reaction rate.
- Light: Some reactions require light for activation.
- Catalyst: Speeds up reaction without being consumed.
- Concentration of reactants: Higher concentration, faster reaction rate.
- Nature of solvent: Solvents can affect the rate by influencing reactant interactions.
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Nature of reactants:
Pharmaceutical Applications of Reaction Kinetics
- Stabilization of drug products: Predicts shelf life and optimal storage conditions to prevent chemical degradation.
- Drug release from dosage forms: Studied in dissolution studies
- Absorption, distribution, and elimination studies: Understanding how drugs behave in the body.
- Explaining drug action: Understanding the rate processes involved in drug action at the molecular level.
Chemical Reactions & Collisions
- Most reactions require collisions between reactant molecules or atoms.
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Effective collisions lead to product formation, which require:
- Correct particle orientation: Collision must be from the right direction for interaction.
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Activation energy (Ea): The minimum energy required for the collision to be effective.
- Molecules must have enough energy to overcome the energy barrier and form products.
Reaction Rates
- Defined as the change in concentration over time.
- Measured in mol L-1 s-1.
- Can be expressed in three ways:
- Average rate: Change in concentration of reactant divided by time interval.
- Instantaneous rate: Rate at a specific point in time.
- Initial rate: Rate at the beginning of the reaction.
- Rate expressions involving reactants typically have a negative sign, since reactant concentrations decrease over time.
Rate of reaction
- The rate of a reaction is the change in concentration of a reactant or product per unit time.
- The rate can be expressed as either a positive or negative value, depending on whether the concentration is increasing or decreasing.
- It is important to take into account the stoichiometric coefficients of the reactants and products when calculating the rate of reaction.
- The rate of reaction will be the same no matter which reactant or product is studied.
Rate Law
- A rate law is a mathematical equation that describes the relationship between the rate of reaction and the concentrations of the reactants.
- Rate laws must be determined experimentally.
- The rate law is typically expressed as a power law, where the exponents indicate the order of the reaction with respect to each reactant.
First-Order Reactions
- A first-order reaction is one in which the rate of reaction is directly proportional to the concentration of one reactant.
- The rate law for a first-order reaction is: rate = k[A], where k is the rate constant.
- The rate constant for a first-order reaction has units of s-1.
- The half-life of a first-order reaction is the time it takes for the concentration of the reactant to decrease by half.
- The half-life is constant and independent of the initial concentration.
Determination of Reaction Order
- The order of a reaction can be determined experimentally by studying how the rate of reaction changes when the concentration of each reactant is varied.
Isolation Method
- The isolation Method is a method used to determine the order of a reaction with respect to each reactant.
- The method involves isolating each reactant in turn and keeping all other reactants in large excess.
- By observing how the rate of reaction changes with respect to the concentration of the isolated reactant, the order of the reaction with respect to that reactant can be determined.
Second-Order Reactions
- A second-order reaction is one in which the rate of reaction is proportional to the square of the concentration of one reactant or to the product of the concentrations of two reactants.
- The rate law for a second-order reaction is: rate = k[A]2 or rate = k[A][B].
Zero-Order Reactions
- A zero-order reaction is one in which the rate of reaction is independent of the concentration of the reactant(s).
- The rate law for a zero-order reaction is: rate = k.
- The half-life of a zero-order reaction is dependent on the initial concentration.
Graphical Methods
- The order of a reaction can also be determined by plotting the concentration of the reactant as a function of time.
- For a zero-order reaction, the concentration of the reactant will decrease linearly with time.
- For a first-order reaction, the natural logarithm of the concentration of the reactant will decrease linearly with time.
- For a second-order reaction, the reciprocal of the concentration of the reactant will increase linearly with time.
Molecularity
- The molecularity of a reaction refers to the number of molecules or ions that collide in a single elementary step.
- Molecularity is a theoretical concept, while reaction order is determined experimentally.
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Description
Explore the principles of reaction kinetics, focusing on factors that influence chemical reaction rates and their mechanisms. This quiz also delves into the pharmaceutical applications, such as drug stabilization and release. Test your understanding of how these concepts apply in the realm of chemistry and pharmacology.
