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Questions tagged [kinetics]

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

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Which is faster- SN1 or SN2?

We were studying about nucleophilic substitution reactions. My professor said that in general SN1 reactions are faster than SN2 reactions. I am unable to understand that how can we generalise the rate ...
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Can I use the quasi-equilibrium approximation when drug and ligand distribution volumes are different?

A drug $D$ binds a ligand $L$ to form a complex $C$ according to the law of mass action. Furthermore, mass balance should be achieved. Can I still assume quasi-equilibrium when the distribution ...
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Chemical Kinetics regarding Iodination of Cyclohexanone

We did an experiment to determine the overall order of iodination of cyclohexanone. Rate of a certain chemical reaction = $\ce{k[A]^p[B]^q[C]^r}$ so the overall order = p+q+r We're referring to a ...
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Chemical kinetics

Consider a reversible reaction $\ce{A}$ converts to $\ce{B}$ and $\ce{B}$ converts to $\ce{A}$ with forward and backward rate constants $k_\mathrm{fwd} = k_\mathrm{rev }= \pu{1 s-1}.$ Suppose we start ...
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Explosive reaction based on reaction rate

Question We have the following chemical reactions: $$ \begin{align} \ce{A + B^* &-> C + D^*}\tag{1}\\ \ce{D^* &-> B^* + B^*}\tag{2}\\ \ce{B^* &-> B}\tag{3} \end{align} $$ ...
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Can reactions take place above decomposition temperature of one of the products?

Can reactions take place above decomposition temperature of one of the products? For example: K2O -> K2O2 + K (above 350°C) K2O2 -> K2O + K (above 500°C) Would the first reaction still take place ...
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38 views

Rate Expression with two products

Consider the two following cases Case 1: Two Same Products Given the following chemical reaction, $$A + B \rightarrow C + C$$ where C are radicals, therefore I am not writing $2C$ on the right ...
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1answer
59 views

Relating collision theory to rate of reaction [closed]

I want to relate the macroscopic advancement of a reaction, the rate of the reaction, with the microscopic collisions of the molecules. This is the type I have developed so far: $$u = A^2 \times \...
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1answer
60 views

How is the ln k term in the linearised Arrhenius equation acceptable?

In my syllabus we only study about rate laws under the topic "Rates of reactions", but as I was interested in it, I started to search about that topic. And then I found the Arrhenius equation $$\ln k ...
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47 views

Does bicarbonation require water?

In an aqueous solution of $\ce{NaOH}$ exposed to the atmosphere one can probably expect some degree of $$\ce{NaOH(aq) + CO2(g) -> NaHCO3 (aq)}$$ But, what would happen if just a solid block of $\...
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139 views

Differentiating between Elementary and Non Elementary reaction [closed]

Is it possible to tell just by looking(reaction's equation) that whether a given is reaction is elementary or non elementary ?
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73 views

Units of the rate constant for reactions whose order is greater than 1

In many textbooks, it is written that: The value of rate constant depends on the nature of the reactants, temperature and catalyst. It is independent of the concentration of the reactants. However,...
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76 views

Thermodynamic vs kinetic basicity [closed]

I'm writing something related to basicity and came across few papers that distinguish thermodynamic and kinetic basicity. "In particular, the study of hydrogen bonding (H-bonding) within proton ...
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130 views

Chaos in chemical reactions

I recently read about Chaos Theory and was wondering if a chemical reaction results in or shows characteristics of chaos (I found a few examples of such reactions here) Chaos theory concerns ...
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Does the activation energy depend upon the stoichiometric coefficient?

For the decomposition of $\ce{N2O5(g)}$ it is given that $$ \begin{align} \ce{2 N2O5(g) &→ 4 NO2(g) + O2(g)} &\quad\text{activation energy} &= E_\mathrm{a}\\ \ce{N2O5(g) &→ 2 NO2(...
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Is activation energy directly related to the reaction rate? (keeping the temperature, concentration, catalyst, particle size and pressure constant)

For different chemical reactions, does the activation energy of that reaction directly relate to the reaction rate? In other words, would a reaction always be slower if it had a higher activation ...
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32 views

What effect does the dye color have on the kinetics of a commercial lightstick?

According to thoughtco: If fluorescent dyes weren't put in glow sticks, you wouldn't see any light at all. This is because the energy produced is usually invisible ultraviolet light. Fluorescent dyes ...
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1answer
97 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 ...
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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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1answer
31 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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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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50 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
39 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
78 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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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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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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37 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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82 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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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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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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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
111 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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156 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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38 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
54 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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374 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
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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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174 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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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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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
41 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
68 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: $$...