Chemical Kinetics Flashcards
the rate at which a chemical reaction occurs
Chemical Kinetics
the minimum amount of energy to cause chemical reactions
Activation Energy
3 factors that affect the rate of chemical reaction
- concentration of reactants
- temperature
- presence of catalyst
the mathematical relationship between the concentrations of the reactants, and the rate of reaction
Rate Law
in A + B -> C + D
write the rate law expression
rate = K [A]^n [B]^m
how to determine n and m in:
rate = K [A]^n [B]^m
only through experimentations
Do you include the reactants and products in the rate law expression?
No, only the reactants are included
What is the order of the following:
1.) rate = k [A] [B]
2.) rate = k [A]^2 [B]
3.) rate = k [A]^0
4.) rate = k [A]^2
5.) rate = k [A]
- 2nd order
- 3rd order
- 0the order
- 2nd order
- 1st order
Find the rate expression for the ff:
aA + bB -> cC + dD
- 1/a Δ[A] / Δt =
- 1/b Δ[B] / Δt =
1/c Δ[C] / Δt =
1/d Δ[D] / Δt
In writing rate expressions, why is the reactants side NEGATIVE, and the products side POSITIVE?
Negative si reactants kasi nababawasan sila to create more products
MOST important thing to remember before writing rate expressions?
BALANCE THE EQ
Are solids and liquids included in the rate expressions?
No, only gas and aq
Differential Rate Law vs Integrated Rate Law
DRL: express how rate depends on concentration
(rate = K [A]^n [B]^m)
IRL: how concentrations depend on time (yung 3 equations based on y=mx+b)
If rate is multiplied by the ff., what is the reaction order?
1
2
4
1/2
0th
1st
2nd
-1st
the time required for one-half of a reactant to react
half-life
In half-life, [A]t is = to?
0.5 [A]0
Write the INTEGRATED RATE LAW and HALF LIFE equations of the following rate laws
rate = k
rate = k [A]
rate = k [A]^2
0th order:
[A]t = -kt + [A]0
t 1/2 = [A]0 / 2k
1st order:
ln[A]t = -kt + [A]0
t 1/2 = ln2 / k
2nd order:
1/[A]t = kt + 1/[A]0
t 1/1 = 1 / k[A]0
How to know what order a reaction is based from a given table (Time in s & Concentration in M)
Kung anong r (linearity constant) ang closer to |1|
In regression calculator, what will you put in x and y axis in figuring out the reaction order?
0th order:
x-axis = time
y-axis = [A]
1st order:
x-axis = time
y-axis = ln [A]
2nd order:
x-axis = time
y-axis = 1/ [A]
What is the meaning of
r
A
B
in regression
r = linearity regression
A = y-intercept (b in y = mx + b)
B = slope/rate constant k (m in y = mx + b)
If the value of B is negative, will the rate constant k be negative also?
No
the slope CAN BE negative, but k CANNOT be
What are the units of K per reaction order?
0th order = M/s
1st order = 1/s
2nd order = 1/M s
What order does the rate of radioactive decay follow?
first order kinetics
What is the formula for the % of radioactive decay after t days
Nt/N0 x 100
What does the collision theory state?
For a chemical reaction to take place, the particles must collide effectively
According to the Collision Theory, what is the relationship between the ff:
- rate of reaction
- frequency of collision
direct relationship
What is the formula of the reaction rate according to the collision theory?
Reaction Rate = # of collisions/time
2 Factors that determine an effective collision
- energy of colliding particles
- orientation of particles
What are formed by reactants as a result of collision?
temporary species
What should be overcome to produce a chemical reaction?
threshold energy (activation energy)
What does the ARRHENIUS EQUATION describe?
describes the temperature dependence of the rate constant
3 equations in Arrhenius Equation
ln k = - Ea / RT + ln A
k = A e ^ (- Ea / RT)
A = k e ^ (Ea / RT)
wherein:
Ea is J/mol
A is collision frequency
R is 8.314 J / mol k
T is temperature in K
In regression calculator, what will you put in x and y axis in arrhenius equation?
x - axis = 1/Temperature
y - axis = ln [k]
In arrhenius equation, how to get Ea and A
Ea = -slope x R
A = e^(y-intercept)
