Rates Of Reaction Flashcards
What is the reaction rate?
The reaction rate is a measure of how fast reactants are converted into products, typically expressed as the change in concentration per unit time.
Define the rate law for a reaction.
The rate law expresses the reaction rate as a function of the concentration of reactants, e.g., Rate = k[A]^x[B]^y.
What does the rate constant (k) represent?
The rate constant is a proportionality factor in the rate law that is specific to a given reaction at a fixed temperature.
What is the reaction order?
The reaction order is the sum of the exponents of the concentration terms in the rate law, indicating how the rate depends on the concentration of reactants.
How does temperature affect reaction rates?
An increase in temperature generally increases reaction rates by providing more energy to overcome the activation energy barrier.
Write the Arrhenius equation.
k = A × e^(–Ea/RT), where A is the frequency factor, Ea is the activation energy, R is the gas constant, and T is the temperature in Kelvin.
What is activation energy (Ea)?
Activation energy is the minimum energy required for reactants to transform into products during a reaction.
“Explain collision theory.”
Collision theory states that a reaction occurs when reactant molecules collide with sufficient energy and proper orientation.
How do catalysts affect reaction rates?
Catalysts lower the activation energy, increasing the number of effective collisions and thus accelerating the reaction rate.
What is the significance of the frequency factor (A) in the Arrhenius equation?
The frequency factor represents the number of collisions per unit time with proper orientation for reaction.
Define half-life in the context of chemical kinetics.
Half-life is the time required for the concentration of a reactant to decrease by half.
How does reactant concentration affect reaction rate?
Increasing the concentration of reactants generally increases the rate by causing more collisions per unit time.
What is the difference between homogeneous and heterogeneous catalysis?
In homogeneous catalysis, the catalyst is in the same phase as the reactants; in heterogeneous catalysis, the catalyst is in a different phase (usually solid) than the reactants.
How can reaction mechanisms be studied experimentally?
By analyzing the reaction rate, intermediates, and the effect of various factors (e.g., temperature, concentration), one can deduce the step-by-step sequence of events in a reaction mechanism.
What information does an energy profile diagram provide?
It shows the activation energy, intermediate steps, and the overall energy change (ΔH) of a reaction.
Describe the effect of pressure on the reaction rate of gaseous reactions.
Increasing pressure typically increases the reaction rate by effectively increasing the concentration of gaseous reactants.
What is the role of molecular orientation in reaction rates?
Correct molecular orientation during collision is crucial for effective collisions and subsequent product formation.
How can the order of a reaction be determined experimentally?
By measuring how changes in reactant concentrations affect the reaction rate and fitting the data to the rate law.
Why is it important to study reaction rates in chemistry?
Understanding reaction rates is essential for controlling industrial processes, predicting reaction behavior, and designing efficient chemical systems.
What are reaction intermediates and how do they affect kinetics?
Intermediates are transient species formed during a reaction; their formation and consumption can provide insight into the reaction mechanism and rate-determining steps.
