Questions tagged [kinetics]
The study of rates and steps in mechanisms of chemical processes.
751
questions
-1
votes
0answers
16 views
Change in concentration of 1st order reaction [on hold]
For the first order reaction $\ce{A → B},$ is the change of concentration of $\ce{A}$ equal to the change of concentration of $\ce{B}$?
And would this be different if you have $\ce{A → B + C}\,?$
2
votes
1answer
23 views
Why is activation energy drawn in a potential energy diagram in reactions?
I learned in chemistry class that activation energy is the av. KE that the colliding particles need in order to successfully react. However, they are always drawn as a "hill" in a PE diagram.
I do ...
1
vote
0answers
23 views
Measuring change in concentration of hydrogen peroxide
I am conducting an experiment to find the rate constant of the decomposition of hydrogen peroxide, $\ce{H2O2}.$ For this, I was planning on using the integrated rate law:
$$\ln(\text{final ...
-3
votes
0answers
20 views
Kinetics question [on hold]
Im giving a reaction A + B -> C
I know the initial concentrations of A, B and C and the rate constant is 1.5 * 10^4 M^-1 s-1
Im tasked to find out the concentration of C after 10 seconds. My ...
3
votes
1answer
29 views
What are the equations giving the molar flow of different molecules linked by a reaction?
Let consider a steady state CSTR in which occurs the following reaction:
$$\ce{aA + bB \leftrightarrow cC}$$
Notations:
$F_i$ is the molar flow of $i$, $r$ is the rate of reaction, $V$ is the ...
-1
votes
0answers
9 views
Uncertainty calculation help! Eyring Plot [closed]
If I am looking at the Eyring equation, lnk/T = −ΔH†/RT + lnkB/h + ΔS‡/R, how can i proceed with my uncertainty calculations?
2
votes
0answers
29 views
Are there any forbidden collisional electronic transitions?
There are spectroscopy selection rules marking some radiative electronic transitions as forbidden. For example, it is stated that single electron of H atom can not move from S2 to S1, or from P2 to S2 ...
2
votes
0answers
29 views
What is the correct definition for the activation Gibbs energy?
i found several definitions of the activation energy in electrochemistry, but i dont know why they are different. For example in Atkins "Physical Chemistry" the activation gibbs energy is defined as:
...
0
votes
0answers
27 views
Solvent effects on SN1 and SN2 reactions [closed]
If polar protic solvents favor $\mathrm{S_N1}$ reactions, does this mean that the rate of reaction should increase on the addition of water or ethanol for example as solvents and should the rate of ...
0
votes
2answers
40 views
Rate law for breakdown of ozone to oxygen
For the following problem:
Example 3: Write the rate law for $\ce{2 O3 -> 3 O2}$ given that the first step is fast and reversible, and the second step is slow.
$$
\begin{align}
&\text{...
3
votes
0answers
47 views
Modelling the Oregonator
Assuming this is the correct place for a post like this, I need to write a piece of code to show the oscillations in the Oregonator. I have successfully done so for the Brusselator, but have been ...
0
votes
1answer
32 views
Value of the frequency factor in the Arrhenius equation [duplicate]
Is the value of 'A' necessarily the same for two different reactions taking place at the same temperature?
It's actually a part of another question which is if the rate constant k1 of a reaction is ...
3
votes
3answers
76 views
Temperature dependence of reaction rates
Is it correct to say that "Increasing the temperature will always increase the rate of any chemical reaction"?
Many articles on the internet and textbooks say yes but what about biochemical reactions ...
3
votes
0answers
18 views
How can I determine the electrode potential of ethanoic acid redox reaction?
I'm conducting a research paper on the effect of surface area ratio from anode to cathode and the electrode material on the rate of electrolysis of ethanoic acid by measuring the volume of carbon ...
2
votes
0answers
36 views
What is the activation energy barrier of uncatalyzed nitrogen fixation?
I'm interested in the activation energy ($E_\mathrm a$) of uncatalyzed aqueous nitrogen fixation:
$$\ce{3 H2 + N2 -> 2 NH3}$$
Biology performs this reaction with the nitrogenase enzyme at room ...
0
votes
0answers
16 views
What causes the duration of the amber periods of the Briggs-Rauscher reaction to first increase and then decrease as the reaction oscillates?
I was collecting experimental data on the Briggs Rauscher reaction and realized that the period of the amber oscillations initially decreased and then started to increase. While I understand the ...
0
votes
0answers
34 views
Conditional kinetic equations
From a biological system, I got the following reaction:
$$A+B+D\rightarrow C+C_1D$$ ($C_1D$ is a certain complex)
However, if at any given time there are no $D$s to react, and only then, instead the ...
2
votes
1answer
51 views
How is the 'rate law' and 'order' for the ozone decomposition reaction can be defined?
How is the 'rate law' and 'order' for the following reaction can be defined?
$$\ce{2O3 -> 3O2}$$
"The expression that correlates the rate of reaction with concentration of reactants is known as ...
1
vote
0answers
17 views
Investigating the effect of solvents on the alkaline hydrolysis of ethyl acetate
In the following reaction, I believe a polar aprotic solvent like propanone will be more favorable since the partial negative charge on the oxygen atom in propanone will attract the sodium ion from ...
1
vote
0answers
23 views
What is the equation that describes the variation in concentration of an inhibitor in an heterogeneous catalysis?
I find myself in quite a pinch: I have to sustain a Chemical Physics exam, and I know for a fact that the professor often asks this particular question:
Suppose that we have both a reacting species ...
1
vote
0answers
21 views
Investigating the effect of solvents (protic vs aprotic) on the alkaline hydrolysis of ethyl acetate using a conductivity meter
What different areas about solvents can be explored with the conductivities collected of the alkaline hydrolysis of ethyl acetate in propanone and ethanol?
$$\ce{CH3COOC2H5 + NaOH -> CH3COONa + ...
2
votes
0answers
35 views
How do fuel/oxidizer combustion mechanics change when the constituents are supercritical?
The problem to solve is this: I want to create a heat generator [or heat absorber] that functions at atmospheric pressure to the pressure at the bottom of the sea. It will be used to drive a Stirling ...
0
votes
0answers
36 views
Reaction rate of Mg with aryl halides
I have been thinking of the rate of reaction of aryl bromide and aryl chloride with $\ce{Mg}$ to form Grignard.
When considering the electronegativities the carbon in aryl chloride is more ...
0
votes
0answers
13 views
Comparing rates of HBr addition to propene and propyne
I was asked to compare the rates of electrophylic addition of HBr (no organic peroxide) to propene and propyne. I thought that the rate of addition to propyne is faster than addition to propene, my ...
0
votes
4answers
98 views
Relation between activation energy and rate constant
Consider two types of reaction. One has more activation than other. If we increasing temperature by same amount in both, rate constant of which reaction will increase more?
My attempt: as we know ...
0
votes
0answers
87 views
Which of the following statements is true if HI is formed in the following reaction?
Which of the following statements is true if HI is formed in the following reaction?
$$\ce{H2(g) + I2(g) -> 2HI(g)}$$
a. There are no collisions between the reactants in the reaction.
...
0
votes
0answers
32 views
intuitive explanation of Wegscheider condition and its violation
The Wegscheider condition restricts the values that rate constants in a set of chemical reactions can take on. can someone please explain intuitively why the condition has to be true, and give a ...
1
vote
1answer
49 views
What does it mean for chemical reaction network to be in equilibrium?
What does being in "equilibrium" mean for a set of chemical reactions? If we have some number $n$ of $\ce{A}$ molecules and $m$ of $\ce{B},$ and the following reaction where $\ce{A}$ and $\ce{B}$ can ...
10
votes
2answers
361 views
Kolmogorov backward equations in active biological systems
I am trying to understand the following equations from a paper by Wang et al. [1, p. 5 at the SI]:
Michaelis–Menten Representation of the Kinesin Cycle
We assumed that there is a strong ...
1
vote
0answers
42 views
Robinson annulation
In the mechanism of Robinson annulation, what is the rate determining step?
I have searched in my book but it is not given. If possible please specify the reason for that step being the RDS.
Thanks in ...
6
votes
1answer
86 views
Equilibrium constant for a solid-solid equilibrium
Suppose there are two equations:
$$
\begin{align}
\ce{A(s) &<=> B(g) + C(s)} &\quad &K_1 \tag{R1}\\
\ce{B(g) &<=> D(s) + E(s)} &\quad &K_2 \tag{R2}
\end{align}$$
...
1
vote
0answers
45 views
Reactivity of Grignard reagent
I had the following question at an exam:
What is the fastest reacting compound towards nucleophilic addition with Grignard reagent?
(a) Acyl chloride
(b) Aldehyde
(c) Ester
It is ...
5
votes
2answers
146 views
Derivation of time probability distributions for single molecule kinetics
If we have a protein $\ce{A}$ that can bind to protein $\ce{B}$:
$$\ce{A + B <=>[$k_\mathrm{fwd,1}$][$k_\mathrm{rev,1}$] AB}$$
and the bound complex $\ce{AB}$ can be converted into $\ce{C}$:
$...
0
votes
0answers
27 views
Rate of reaction
For a reaction say
$$\ce{nA->B}$$ with $$\text{rate} =k[A]^n$$
So do we write rate as $ \frac {-\mathrm d[A]}{\mathrm dt}$ or $\frac{1}{n} \frac {-\mathrm d[A]}{\mathrm dt}$ We have only been ...
0
votes
1answer
45 views
Is activation energy time-dependent?
I was thinking lately about activation energy's dependency on time. I couldn't find any information on the internet. Only answer that came up to my mind is the fact that activation energy is constant, ...
0
votes
1answer
39 views
Microscopic and mechanical approach to boiling point [duplicate]
I am confused as to how I should visualize the boiling process throughout a liquid.
From my understanding, the boiling point of a liquid is when its vapor pressure reaches atmospheric pressure. This ...
1
vote
2answers
54 views
Rate law of the reaction of propane with oxygen
In class, I have a demonstration where I light a bubble filled with propane. As I add oxygen, the bubbles combust faster and more quickly. I have already balanced out the chemical reaction like so:
$$...
3
votes
1answer
70 views
Distribution of polymer lengths
Suppose we have a chemical reaction where a linear chain can form (reversibly) from building blocks (e.g. atoms or molecules):
$$\ce{X_$i$ + X_$k$ <=>[$k_\mathrm{fwd}$][$k_\mathrm{rev}$] X_$i$...
0
votes
0answers
15 views
Where can I find equilibrium constants for a specific reaction? [duplicate]
I'm doing a project on the production of dap fertilizer, but I can not find a database with kinetics constants(reaction rate constant.)
It's based on TVA Process for production of granular diammonium ...
4
votes
2answers
60 views
Y-axis of the reaction co-ordinate graph
In the graph of the reaction co-ordinate, is the $y$-axis that is used $∆H,$ $∆U$ or $∆G$?
1
vote
1answer
70 views
Why does the rate of the reaction decrease with an increase in temperature?
Why does the following reaction
$$\ce{2NO + O_2 -> 2NO_2}$$
have negative reaction coefficient, i.e., why does the rate of the reaction decrease with an increase in temperature ?
I have been ...
1
vote
2answers
61 views
Implication of negative order on kinetics
In the reaction
$$\ce{2 O3 -> 3 O2}$$
the order of reaction that I have been taught is
$$\ce{O_3 \underset{$k_{-1}$}{\overset{$k_{1}$}{<=>}} O_2 + O}$$
$$\ce{O_3 + O \overset{$k_{2}$}{->...
1
vote
0answers
33 views
Why is the nucleophilic substitution of OH- with 1-bromopentane slower than with 2-bromo-2-methylbutane?
Which statement about the reaction of a hydroxide ion with the organic reagent is correct?
A. 1-bromopentane predominantly follows an $\mathrm{S_N1}$ mechanism.
B. 2-bromo-2-methylbutane ...
0
votes
0answers
31 views
Do all zero order reactions occur as combination of multiple elementary reactions?
In a reaction, the rate determining step (RDS) gives the order of reaction. There might be 2 or 3 molecules colliding to give a product (2nd or 3rd order) or a molecule breaks for order 1. But for ...
2
votes
0answers
40 views
Gibbs free energy of activation and activation energy [duplicate]
What the difference between Gibbs free energy of activation and activation energy
1
vote
1answer
53 views
Equilibrium constant for a multi-step reaction [closed]
If a reaction proceeds in steps, is the equilibrium constant of every step taken into account to arrive at the final constant? Or can we just calculate equilibrium constant for the overall reaction ...
1
vote
0answers
33 views
Reaction Mechanism with a Rate Determining Step
Just a quick question on how to deal with multiple intermediaries in a proposed reaction mechanism.
Here is the overall reaction:
$$\ce{I-(aq) + OCl-(aq) -> IO-(aq) + Cl-(aq)}$$
Here is the ...
0
votes
0answers
34 views
First order reaction
I am little bit confuse about relating the half life time period of a first order reaction something like
$$\ce{2A -> B + C}$$
Here the rate of reaction will be half of the rate at which $\ce{A}$ ...
0
votes
1answer
33 views
Organic reaction rate equations needed [closed]
Where to find a list of common organic reaction rate laws?? Anybody has this?? I could not find one on internet
0
votes
1answer
35 views
Which of the following procedures will allow the student to determine the rate constant, for the reaction? [closed]
Is the answer A or B because C and D won't give me the rate constant?
