Focusing on and Expressing Reaction Rate
________ _______ is the study of reaction rates and the factors that affect them.
What is Chemical Kinetics?
The term k is the ____ _______, which is specific for a given reaction at a given temperature and does not change as the reaction proceeds.
What is the rate constant?
An integrated rate law includes ____ as a variable
What is time?
An increase in the concentration of a reactant leads to a _______________ number of collisions, hence increasing reaction rate.
What is increase?
The individual steps of the reaction mechanism are called _________ _____ because each one describes a single molecular event. Each elementary step is characterized by its ___________, the number of reactant particles involved in the reaction.
What is elementary steps? What is molecularity?
Reaction rate is the change in the ________________ of reactants or products as a function of time.
What is amount?
The exponents m and n are reaction orders and are determined ___________________________. Reaction orders define how the rate is affected by reactant concentration.
What is experimentally?
For a first-order reaction, does t1/2 depend on the starting concentration?
What is false?
Concentrations are __________ in the rate law, not added (laws of probability).
What is multiplied?
The slowest step in a reaction is the ___________. The rate law for the rate-determining step becomes the rate law for the overall reaction.
What is rate-determining?
What are three factors that affect reaction rate?
What are concentration of reactants (number of collisions), physical state of reactants and temperature?
If the rate does not change when [A] doubles, the rate does not depend on [A], and the reaction is _____________________ with respect to A:
What is zero order?
Radioactive decay is a _____ ______ process. The half-life for a radioactive nucleus is a useful indicator of its ________________.
What is first order? What is stability?
Collisions must occur with enough energy to allow bond-breaking to occur. The energy threshold that the colliding molecules must exceed in order to react is the ____________.
What is activation energy?
A ______ is a substance that increases the reaction rate without itself being consumed in the reaction.
What is catalyst?
The higher the temperature, the concentration, and the mixing of reactants, the _________________ the reaction rate.
What is faster?
If the rate doubles when [A] doubles, the rate depends on [A]1 and the reaction is _____________________ with respect to A.
What is first order?
For the general reaction A + B → product, the rate law is found to be rate = k[A][B]. Under what conditions is this rate law most similar to rate = k[A]?
What is [B] > [A]
Explanation: When the concentration of B is very large compared to A, the change in concentration of A is much more significant than the change in concentration of B (the concentration of B is nearly constant). The rate is observed to depend strongly on the concentration of A.
If reactant molecules collide with a certain minimum energy, they reach an ____________________, from which they can change to products.
What is an activated complex?
A catalyst will speed up both the ______________ and the _____________ reactions.
What is forward and reverse?
Define average rate, instantaneous rate and initial rate.
What is:
Average rate is the slope of the line joining two points along the curve over a given period of time.
Instantaneous rate is the slope of a line tangent to the curve at any point in time.
Initial rate is the instantaneous rate at the moment the reactants are mixed (at t = 0).
If the rate quadruples when [A] doubles, the rate depends on [A]2 and the reaction is _____________________ with respect to A.
What is second order?
Which of the following statements correctly describe the half-life of a reaction? Select all that apply.
A. The half-life of a first-order reaction is independent of the initial concentration.
B. The half-life of a reaction is the time taken for [A]0 to drop to half its original value.
C. The half-life of a reaction is related to its rate constant.
What is A, B, and C?
The kinetic molecular theory of matter assumes that in order for a reaction between two particles to take place, the particles must first ______.
What is collide with each other?
Explanation: Particles must be oriented correctly relative to each other for a collision to be effective, but they do not slow down to achieve this. The particles must collide with sufficient energy to make the collision effective, but they do not speed up in order to collide.
What three criteria must a valid mechanism meet?
What is:
1. The elementary steps must add up to the overall balanced equation.
2. The elementary steps must be reasonable. They should generally involve one or two reactant particles.
3. The mechanism must correlate with the experimentally observed rate law.