Term
What is the order of a plot of reactant concentration vs. time that has a straight line? 

Definition


Term
What does not increase the value of the rate constant for a reaction? 

Definition
Increasing the [] of reactants 


Term
A certain reaction has an enthalpy of 75kJ and an Ea of 40kJ. A catalyst lowers the activation energy of the forward reaction by 15kJ. What is the Ea of the reverse reaction with the same catalyst? 

Definition
Ea=40kJ Catalyst(15)= 25kJ Reverse reaction(+75)= 100kJ 


Term

Definition
It increases the rate of the reaction and lowers the activation energy. (Makes the curve less steep.) 


Term

Definition
The minimum energy required to turn reactants into products. 


Term
At a certain temp., the first order decomposition of H202 exhibits these data: time (seconds, s) 0 15
[H202] (mol L^1) 2.0 1.0
At what time will the [H2O2]=0.50 mol L^1? 

Definition
(This is first order, so you can't find the equation of the line). Concentration decrease by 1/2 every 15 seconds, so the concentration will be 0.50 after 30 SECONDS. 


Term
The rate of a reaction with just two reactants is observed to double when the concentration of one reactant is doubled and the second reactant is held constant. The rate is also observed to increase by a factor of nine when the concentration of the second reactant is tripled, holding the concentration of the first reactant constant. What is the overall order for this reaction? 

Definition


Term
Tritium decays by a firstorder process that has halflife of 12.5 years. How many years will it take to reduce the radioactivity of a tritium sample to 15% of it original value? 

Definition
t 1/2= 0.693/k k=0.05544 ln(0.15)=0.005544t t=34 yr 


Term
What step limits reaction rate? 

Definition


Term
What is the overall order of a reaction with a rate constant having the units L•mol1•s1? 

Definition


Term
When reacted with water, the insecticides DDT decomposes with a halflife of 10 years. Approximately how many years will it take for 99% of a given sample to decompose once exposed to water in the environment? 

Definition
t 1/2= 0693/k 10= 0.693/k k=0.0693 ln(0.01)=0.0693t t=70 yr 


Term
What, if decreased, will increase the rate of a reaction of a solid? 

Definition


Term
What reaction characteristic is changed by adding a catalyst to a reaction at constant temp? 

Definition


Term
Which statement is true for the general rate law: Rate = k[A]m[B]n? A)The exponents in the rate law must be positive integers. B)The values for the exponents must be determined by experiment. C)The overall order of the reaction is equal to m times n. D)It can be written from the stoichiometry of the overall reaction. 

Definition


Term
Does a catalyst lower the Ea for the forward reaction, reverse reaction, or both? 

Definition


Term
In the following reaction, what is the relationship between the rate of production of NH3 and rate of consumption of H2?
N2(g)+3H2(g)=2NH3(g) 

Definition
△[N2]/△t= (1/3)△[H2]/△t = (1/2)△[NH3]/△t 


Term
For each of the following rate equations, describe what would happen to the rate if the concentration of reactant A was tripled and the concentration of reactant B is halved. a. Rate = k[A][B] b. Rate = k[A]2[B] c. Rate = k[A]2[B]2 d. Rate = k[A][B]3 

Definition
a. increases by 3/2 b. increases by 9/2 (3^2/2) c. increases by 9/4 (3^2/2^2) d. increases by 3/8 (3/2^3) 


Term
At 150C the decomposition of acetaldehyde CH3CHO to methane is a first order reaction. If the rate constant for the reaction at 150C is 0.029 min1, how long does it take a concentration of 0.050 mol L1 of acetaldehyde to reduce to a concentration of 0.040 mol L1? 

Definition
ln[A]=kt+ln(A0) ln(0.040)=(0.029)t+ln(0.050) t=7.7 minutes 


Term
The decomposition of hydrogen iodide into hydrogen and iodine is a second order reaction. The rate constant k = 0.080 L mol1s1. How long does it take an initial concentration of 0.050 M to decrease to half this concentration? 

Definition
t 1/2= 1/k[A0] 1/(0.080)(0.050)= 250 seconds 


Term
The gasphase decomposition of nitrous oxide has the following twostep mechanism.
1) N2O = N2+O2 2) O+N2O = N2+O2
Write the overall equation.
Is O a catalyst or intermediate?
Identify the lower step is the rate law = k[N2O]. 

Definition
2N20 = 2N2+O2
It is an intermediate because it was formed during the middle step of the reaction.
Step 1 (less reactants) 


Term
As concentration increases, rate ________. 

Definition


Term
What is the differential rate law for a zero order, first order, and second order reaction? 

Definition
Zero: r = k (unit= m/s) 1st: r = k[A] (unit= s^1) 2nd: r = k [A]2 (unit= L/(mol•s) 


Term
What is the integrated rate law for zero, first and second order reaction? 

Definition
Zero [A]=kt+[A]0 1st ln[A]=kt=ln[A]0 2nd 1/[A]= kt+ 1/[A]0 


Term
What are the rules of collision theory? 

Definition
•particles must collide •sufficient energy •correct orientation of particles 


Term
Find the overall reaction:
Cl2(g)⇌2Cl(g) (fast) Cl(g)+ChCl3(g)=HCl+CCl3 (slow) Cl(g)+CCl3(g)=CCl4 (fast) 

Definition


Term
Find Ea if:
1) At 701k, rate constant= 2.57 L/mol•s 2) At 895k, rc= 567 L/mol•s 

Definition
ln(k2/k1)=(Ea/r)(1/T11/T2) ln(567/2.57)=(Ea/8.314)(1/7011/895) Ea= 14,500 kJ/mol 


Term
Write overall reaction:
2NO(g)⇌N2O2(g) (fast) H2(g)+N2O2(g)=H2O(g)+N2O(g) (slow) N20(g)+H2(g)=N2(g)+H20(g) (fast) 

Definition
2NO+2H2=2H20+N2
r= k3[H2][N2O2]
k1[NO2]=k2[N2O2]
2NO+2H2=2H2O+N2 r= k3[H2][N2O2]= k3[H2](k1[NO]/k2)= (k3k1/k3)[H2][NO] r= k[H2][NO]^2 


Term
A certain reaction has the following general form: aA ==> bB
At a particular temperature and [A]0 = 2.00 x 10^2 M, concentration versus time data were collected for this reaction, and a plot of ln[A] versus time resulted in a straight line with a slope value of 2.97 x 10^2 min^1.
a) Determine the rate law, the integrated rate law, and the value of the rate constant for this reaction. b) Calculate the halflife for this reaction. c) How much time is required for the concentration of A to decrease to 2.50 x 10^3 M? 

Definition
a) k= [A] ln[A]= 0.0297t+ln[0.0200] k= 0.0297 m/s b) t 1/2= 0.693/0.0297= 23.3 minutes c) ln(0.00250)= 0.0297t+0.0200 t= 202.4 minutes 

