Questions tagged [kinetics]

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

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10 views

How does temperature affect the activation energy?

I know that it affects the reaction by increasing the energy of particles so that more of them have a higher or equal energy than the activation energy. However, when I look at a rate equation and ...
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23 views

A “function of proportionality” in a rate law

I am currently studying rate laws and the determination of the order of a reaction. So first-order reactions remind me of linear functions $f(x)=kx$ while second-order reactions remind me of quadratic ...
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How does the temperature affect the frequency factor?

I am a high school student and have been trying to learn how the temperature affects the frequency factor. I did not even understand the equation below, which is from this site. Can anyone please ...
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56 views

Are the reaction rates of these equations equal?

$$\ce{CH3CH2CH2Br + OH- -> CH3CH2CH2OH + Br-}$$ $$\mathrm{rate} = k[\ce{CH3CH2CH2Br}][\ce{OH-}]$$ If I change the $\ce{Br}$ with any element from halogens (without changing concentration, volume, ...
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Stoichiometry in rate law [closed]

When are the stoichiometric coefficients equal to the exponents of concentration in rate law r=k[a]^m?
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Enthalpy and Activation Energy [closed]

Could you help me with this question, please? In an exothermic reaction: A- The activation energy depends on the energy released. B- Products energy is lower than reactants energy and that depends on ...
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29 views

Using calculus to find the rate of a bivariate reaction

Recently, I've been learning about rates and have found the concept fairly easy to understand in the case of a reaction with a single reactant, which is essentially solving $$f'(t) = kf(t)^n$$ where $...
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53 views

The reaction rate when the rate-determining step has a back reaction

For some reason, I am reviewing general chemistry and I find that the elementary reaction for the rate-determining step (RDS) is assumed to be irreversible, that is, single arrow, in all questions ...
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28 views

Sum of a rate constant gives the total decay rate

I want to ask a question about the sum of a rate constant to yield the total decay rate. From previous studies, the rate of a reaction can be expressed evidently as $$\ce{v_{rate} = k[A]}$$ where ...
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Rate determining step in oxidation of alcohols using chromium-related compounds

I wanted to ask a question about the kinetics of an oxidation reaction using chromium reagents. I was given a lecture today on the mechanism of alcohol oxidations using Chromate (VI) reagents: My ...
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1answer
51 views

How much oxygen is formed in this first order reaction? [closed]

We have a reaction $$\ce{2N2O5 -> 4NO2 + O2},$$ which has a rate constant $k=6,2\cdot10^{-4}/\mathrm{min}$ at temperature $T=318.15\ \mathrm{K}$. How much oxygen is formed in litres when $1.00\ \...
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Literature value for the activation energy of the reaction between hydrochloric acid and sodium bicarbonate

Does anybody have the literature value for the activation energy of the reaction between hydrochloric acid and sodium bicarbonate? If yes, could you please cite the source for it and the value? I ...
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Why do the NMR peaks shift when H+ concentration and temperature are varied on the reversible hydrolysis of pyruvic acid to 2,2-dihydroxypropionate? [closed]

We performed two experiments. Each of the peaks are referring to the methyl peaks in both reactant and product of the hydrolysis reaction. We varied $\ce{H+}$ concentration of the reaction and the ...
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96 views

Order of reaction in adsorption process

(1) $\ce{PH3(g) <=>[W]PH3(adsorption)->[W]P(s) + 3/2 H2(g)}$ The decomposition of phosphine on tungsten surface at low pressure is a pseudo first order reaction. This is because the rate of ...
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23 views

Convert to NASA polynomial format for chemical kinetic calculations

I have calculated thermodynamic properties of a metal oxide through DFT calculations, I want to convert it to NASA polynomial format and use those thermodynamic properties along with rate constants ...
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1answer
40 views

Order of reaction for hydrogen ions being ignored

I have been reading through a case study about calculating the order of reaction for the following reaction: $$\ce{H2O2 + 3 I- + 2 H+ -> I3- + 2 H2O}$$ The paper uses an iodine clock reaction ...
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32 views

Why do statistical effects impact stepwise stability constants?

I have a question regarding the stepwise stability constants of metal complex formation/substitution. My lecture notes say that if we have a metal complex, say $\ce{[MX_{6}]}$, and a substitution ...
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1answer
54 views

Finding change in activation energy from change in rate constant in catalysis

I need to find by how much the activation energy decreases when the rate constant increases by a '$x$' factor when a catalyst is used in the reaction. I'm just super confused about how to solve this....
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107 views

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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51 views

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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400 views

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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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
60 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
66 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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51 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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365 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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100 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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1answer
96 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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148 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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48 views

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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41 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
156 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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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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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
51 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
80 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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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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364 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 ...