Chem Chp. 5 Chemical Kinetics

Question 1

What is Arrhenius’s equation?

Answer 1

k = Ae^-Ea/RT; k = rate constant, A = frequency factor, Ea = activation energy, R = ideal gas constant, and T = temperature in kelvins

Question 2

Explain the relationships of the variables in Arrhenius’s equation.

Answer 2

low activation energy (Ea) and high temperature (T) make the negative exponent of Arrhenius’s equation smaller in magnitude and thus increase the rate constant (k). An increase in frequency (A) also increases the rate of constant (k)

Question 3

What is activation energy?

Answer 3

the energy required to reach the transition state or the energy difference between the transition state and the reactants

Question 4

What is the diff between exo and endergonic energy?

Answer 4

+ change in G = endergonic = energy absorbed
- change in G = exogenic = energy given off

Question 5

What is the rate law?

Answer 5

rate = k [A]^x * [B]^y in mols/sec

Question 5

What is a zero-order reaction?

Answer 5

one in which the rate formation of the product is independent of the changes in the concentration of any reactants, as such, the concentration reaction rate is equal to the rate constant (k)

Question 6

What are the only factors that can change the rate of a zero-order reaction?

Answer 6

changing temperature because increasing temperature increases the kinetics of a reaction. adding a catalyst lowers the reaction’s activation energy, thereby increasing the value of k.

Question 7

What is the concentration vs. time graph of a zero-order reaction?

Answer 7

a linear graph where the slope is negative k

Question 8

What is a first-order reaction?

Answer 8

has a rate that is directly proportional to one reactant, such that doubling the concentration of that reactant results in a doubling of the rate of formation of the product

Question 9

What is an example of a first-order reaction?

Answer 9

radioactive decay

Question 10

What is the concentration vs. time graph of a first-order reaction?

Answer 10

nonlinear, where the slope of ln[A] is negative k

Question 11

What is a second-order reaction?

Answer 11

has a rate that. is proportional to either the concentrations of 2 reactants or to the square of the concentration of a single reactant

Question 12

What is the concentration vs. time graph of a second-order reaction?

Answer 12

nonlinear, where the slope of 1/[A] is equal to k

Question 13

What is Gibbs’s free energy

Answer 13

the change in G determines whether or not a reaction is spontaneous

Question 14

What is the rate-limiting step?

Answer 14

the slowest step that limits the maximum rate at which the creation can proceed

Question 15

What are the factors that can affect the reaction rate?

Answer 15

increasing the concentration of reactants will increase the reaction rate in first and second-order reactions. increasing the temperature and adding a catalyst will increase the reaction rate. changing the medium can increase or decrease the reaction rate depending on how the reactant interact with the medium