Questions tagged [kinetics]

The study of rates and steps in mechanisms of chemical processes.

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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 $\ce{A → B + C}\,?$
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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 ...
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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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: ...
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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 ...
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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{...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 + ...
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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 ...
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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 ...
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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 ...
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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 ...
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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. ...
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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 ...
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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 ...
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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 ...
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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 ...
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1answer
86 views

Equilibrium constant for a solid-solid equilibrium

Suppose there are two equations: $$ \begin{align} \ce{A(s) &<=> B(g) + C(s)} &\quad &K_1 \tag{R1}\\ \ce{B(g) &<=> D(s) + E(s)} &\quad &K_2 \tag{R2} \end{align}$$ ...
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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 ...
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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 $\ce{C}$: $...
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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 ...
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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, ...
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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 ...
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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: $$...
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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_$i$...
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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 ...
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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 $∆G$?
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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 ...
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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{$k_{2}$}{->...
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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 ...
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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 ...
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0answers
40 views

Gibbs free energy of activation and activation energy [duplicate]

What the difference between Gibbs free energy of activation and activation energy
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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 ...
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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 ...
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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 $\ce{A}$ ...
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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
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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?