Question

Part A A certain first-order reaction has a rate constant of 2.40×10−2 s−1 at 21 ∘C. What is the value of k at 61 ∘C if Ea = 90.0 kJ/mol ? Express your answer using two significant figures. k = s−1 SubmitMy AnswersGive Up

Part B A certain first-order reaction has a rate constant of 2.40×10−2 s−1 at 21 ∘C. What is the value of k at 61 ∘C if Ea = 104 kJ/mol ? Express your answer using two significant figures. k = s−1 SubmitMy AnswersGive Up

Answer #1

According to Arrhenius Equation , K = A e -Ea / RT

Where

K = rate constant

T = temperature

R = gas constant = 8.314 J/mol-K

Ea = activation energy=90J=90*10^3J

A = Frequency factor (constant)

Rate constant, K = A ^e - Ea / RT

log K = log A - ( Ea / 2.303RT ) ---(1)

If we take rate constants at two different temperatures, then

log K = log A - ( Ea / 2.303RT ) --- (2)

& log K' = log A - (Ea / 2.303RT’) ---- (3)

Eq (3 ) - Eq ( 2 ) gives

log ( K' / K ) = ( Ea / 2.303 R ) x [ ( 1/ T ) - ( 1 / T' ) ]

Given K=240*10^-2 s^-1

K'= ?

T= 21oC=21+273=294 K

T'= 61oc= 61+273= 334 K

Plug the values we get K'= 1.97 s^-1

Similarly when Ea= 104 kJ/mol K'= 4.0*10^-2 s^-1

Part A
A certain first-order reaction has a rate constant of
3.00×10−2 s−1 at 25 ∘C . What is the value of k
at 69 ∘C if Ea = 77.0 kJ/mol ?
Express your answer using two significant figures.
Part B
Another first-order reaction also has a rate constant of
3.00×10−2 s−1 at 25 ∘C . What is the value of k
at 69 ∘C if Ea = 115 kJ/mol ?
Express your answer using two significant figures.

A certain first-order reaction has a rate constant of
2.30×10−2 s−1 at 25 ∘C . What is the value of k
at 63 ∘C if Ea = 74.0 kJ/mol ?
Express your answer using two significant figures.
Part B
Another first-order reaction also has a rate constant of
2.30×10−2 s−1 at 25 ∘C . What is the value of k
at 63 ∘C if Ea = 128 kJ/mol ?
Express your answer using two significant figures.

-(a) A certain first-order reaction has a rate
constant of 2.75 × 10–2 s–1 at 20 °C. What is
the value of k at 60 °C if Ea
= 75.5 kJ/mol?
(b) Another first-order reaction also has a
rate constant of 2.75 × 10–2 s–1 at 20 °C.
What is the value of k at 60 °C if
Ea = 125 kJ/mol?
(c) What assumptions do you need to make in
order to calculate answers for parts (a) and (b)?

Rate constants for the reaction
NO2(g)+CO(g)?NO(g)+CO2(g)
are 1.3M?1s?1 at 700 K and 23.0M?1s?1 at 800 K.
Part A
What is the value of the activation energy in kJ/mol?
Ea =
134
kJ/mol
SubmitMy AnswersGive
Up
Correct
Part B
What is the rate constant at 770K ?
Express your answer using two significant figures.
k =
/(M?s)

Another first-order reaction also has a rate constant of
3.00×10−2 s−1 at 15 ∘C. What is the value of k
at 67 ∘C if Ea = 131 kJ/mol ?

Calculate the equilibrium constant at 25 ∘C for each of the
following reactions: Part A Cd(s)+Sn2+(aq)→Cd2+(aq)+Sn(s) Express
your answer using one significant figures. K = 6×108 SubmitMy
AnswersGive Up Correct Part B 2Al(s)+3Cd2+(aq)→2Al3+(aq)+3Cd(s)
Express your answer using one significant figures. K = 5×10127
SubmitMy AnswersGive Up Correct Part C
Cr2O2−7(aq)+6Fe2+(aq)+14H+(aq)→2Cr3+(aq)+6Fe3+(aq)+7H2O(l) Express
your answer using one significant figures. K = 2•1057 SubmitMy
AnswersGive Up
Just need Part C

Part A The rate constant for a certain reaction is k = 2.40×10−3
s−1 . If the initial reactant concentration was 0.650 M, what will
the concentration be after 18.0 minutes? Express your answer
with the appropriate units.
Part B
A zero-order reaction has a constant rate of
4.50×10−4M/s. If after 40.0 seconds the
concentration has dropped to 4.50×10−2M, what
was the initial concentration?
Express your answer with the appropriate units.

A particular first-order reaction has a rate constant of 1.35 ×
102 s-1 at 25.0°C. What is the magnitude of k at 45.0°C if Ea =
55.5 kJ/mol?

Part A
A certain first-order reaction (A→products) has a rate constant
of 7.20×10−3 s−1 at 45 ∘C. How many minutes does it take
for the concentration of the reactant, [A], to drop to 6.25% of the
original concentration?
Express your answer with the appropriate units.
Answer:
6.42 min
Part B
A certain second-order reaction (B→products) has a rate constant
of 1.35×10−3M−1⋅s−1 at 27 ∘Cand an initial
half-life of 236 s . What is the concentration of the reactant B
after...

Part A The activation energy of a certain reaction is 30.6
kJ/mol . At 22 ∘C , the rate constant is 0.0110s−1. At what
temperature in degrees Celsius would this reaction go twice as
fast? Express your answer with the appropriate units. Hints T2 = 39
∘C SubmitMy AnswersGive Up Correct Part B Given that the initial
rate constant is 0.0110s−1 at an initial temperature of 22 ∘C ,
what would the rate constant be at a temperature of 170....

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