Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
33 Cards in this Set
- Front
- Back
What is the mechanism of a reaction?
|
It is the actual series of steps through which a chemical reaction occurs
|
|
What is the slowest step in a proposed mechanism called?
|
It is called the rate-determining step
|
|
What is rate?
|
For nearly all forward, irreversible reactions, the rate is proportional to the product of the concentrations of the reactants
|
|
What is the overall order of a reaction (reaction order) definsed as?
|
It is defined as the sum of the exponents, usually equal to x + y
|
|
What are zero-order reactions?
|
They have a constant rate, which is independent of the reactants’ concentrations
|
|
What is the rate law for a zero order reaction?
|
It is rate = k
|
|
What is a first-order reaction?
|
It has a rate proportional to the concentration of one reactant
|
|
What is the rate law for a first order reaction?
|
It is rate = k[A] or rate = k[B]
|
|
What is an example of a first order reaction?
|
Radioactive decay
|
|
What are second-order reactions?
|
It has a rate proportional to the product of the concentration of two reactants, or to the square of the concentration of a single reactant
|
|
What are some examples of a second-order reaction?
|
Rate = k[A]2, rate = k[B]2, or rate = k[A][B]
|
|
What are mixed-order reactions?
|
They have a fractional order, ie rate = k[A]1/3
|
|
What does the collision theory of chemical kinetics state?
|
It states that the rate of a reaction is proportional to the number of collisions per second between the reacting molecules
|
|
What is an effective collision?
|
It is one that leads to the formation of products
|
|
When does it occur?
|
It only occurs when the molecules collide with correct orientation and sufficient force to break the existing bonds and form new ones
|
|
What is the minimum energy of collision necessary for a reaction to take place called?
|
It is called the activation energy, or the energy barrier
|
|
What is a transition state?
|
It is when the old bonds are weakened and the new bonds are beginning to form
|
|
What is a transition state also called?
|
An activated complex
|
|
What is the enthalpy change of the reaction?
|
It is the difference between the potential energy of the products and the potential energy of the reactants
|
|
What does a negative enthalpy change indicate?
|
It indicates an exothermic reaction
|
|
When does the rate of reaction increase?
|
It increases if there is an increase in the number of effective collisions, or a stabilization of the activated complex compared to the reactants
|
|
How do reactant concentrations influence rate?
|
The greater the concentrations of the reactants, the greater the number of effective collisions per unit time, and therefore the reaction rate will increase for all but zero order reactions
|
|
How does temperature influence rate?
|
For nearly all reactions, the reaction rate will increase as the temperature of the system increases
|
|
How does the medium in which a reaction takes place affect rate?
|
The rate of reactions may also be affected by the medium. Certain reactions proceed more rapidly in aqueous solution, whereas other reactions may proceed more rapidly in benzene
|
|
How do catalysts work?
|
They increase reaction rate without themselves being consumed
|
|
What occurs in homogenous catalysis?
|
The catalyst is in the same phase as the reactants
|
|
What occurs in heterogeneous catalysis?
|
The catalyst is in a distinct phase
|
|
What is equilibrium?
|
It is when there is no net change in the concentrations of the products and reactants
|
|
What is the equilibrium constant?
|
Kc, is the concentrations of the products are divided by the concentrations of the reactants
|
|
What is Le Chatelier’s principle used for?
|
It is used to determine the direction in which a reaction at equilibrium will proceed when subjected to a stress, such as a change in concentration, pressure, temperature, or volume
|
|
What does change in concentration do?
|
Increasing the concentration of a species will tend to shift the equilibrium away from the species that is added
|
|
What does a change in pressure do?
|
It causes a change in volume
|
|
What does a change in temperature do?
|
If it is an exothermic reaction, and you add cold, the reaction would shift to produce heat
|