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Questions tagged [kinetics]

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

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How long must a sample last in a molecular dynamics run for it to be considered non-labile?

So I have a few unusual molecules and I wanted to know whether or not they are kinetically stable (non-labile) across a certain range of temperatures. The methods for synthesizing these molecules isn'...
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Why does the rate law of Cannizzaro reaction include a term for base?

The rate law of Cannizzaro reaction in mild base is $$\mathrm{rate_1} = k[\ce{RCHO}]^2 [\ce{OH^-}],\tag{1}$$ while in concentrated base the rate becomes $$\mathrm{rate_2} = k[\ce{RCHO}]^2[\ce{OH^-}]^2\...
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Frequency to induce nitrogen inversion

I would like to know how to compute the frequency at which nitrogen inversion happens in ammonia gas at STP. The activation energy for such process is 24.2 kJ/mol, therefore I thought that it is ...
crisecon's user avatar
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pH at maximum concentration of a certain species (Phosphoric acid) [closed]

I am trying to find the pH at which $[H_{2}PO_{4} ^{-}]$ is maximum by only knowing the pKas. I have tried to derive an equation using kinetics but it failed [1]. After taking a look at the Sillén/...
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Iminium formation rate between formaldehyde and secondary amine

Given the significantly more favored hydrate of formaldehyde in the presence of water under neutral conditions, can we say that this is the slow step in iminium formation? Would removing water/working ...
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Can increasing concentration of reactants make the RDS no longer the slowest step in the mechanism?

The rate determining step is said to determine the overall rate of reaction because it is the slowest step in the mechanism. However, increasing the concentrations of reactants in this step can ...
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Energetic stability and rate of reaction of organic compounds

I am currently taking organic chem for biologists (meaning the level, or the depth, we go into is easier than what a chemist would learn). What is the relation between Energetic stability and the rate ...
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How can a Michaelis–Menten formalism be used when enzyme concentration isn't constant?

I understand that $V_\mathrm{max} = k_3[\ce{E}]_0$ in ordinary Michaelis–Menten (MM) kinetics. According to the lecture notes provided by my university (I don't believe they are available online), ...
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Could an airborne swarm of small insects explode? [closed]

I know that fine-grained organic matter such as flour or pollen can be quite explosive if ignited. It also seems logical to me that the explosiveness of such an organic powder is determined by many ...
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Why does iodate and acidified metabisulfite solution turn yellow instead of blue at high temperatures (above 50)

We are doing a kinetics investigation at school where we are trying to find the activation energy of the reaction between potassium iodate and sodium metabisulfite. Solution A contains 2g of potassium ...
abc's user avatar
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Is it possible to calculate the theoretical rate of reaction?

I am conducting an experiment where I will be changing concentration (0.2 mol/dm3, 0.4 mol/dm3, 0.6 mol/dm3, 0.8 mol/dm3, 1.0 mol/dm3) and seeing how that affects the rate of reaction for a reaction ...
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How is it even possible that vapour pressure of liquid and vapour of solid are equal at freezing point? [duplicate]

My text book states The freezing point is defined as "the temperature at which the vapor pressure of the substance in its liquid phase is equal to its vapor pressure in the solid phase" Also ...
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Define a rate-determining step and an energy barrier for a multi-step reaction profile

I am currently making reaction profile by means of DFT calculations. I am able to correctly draw a whole reaction profile. However, I am struggling to find what exactly is the energy barrier of a ...
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Why is reaction rate proportional to the order of reactants? [duplicate]

I know that for some elementary reaction $m\text{A}+n\text{B}\rightarrow\text{C}$, the rate of reaction is given by $-\frac{\text{dA}}{\text{dt}}=k[\text{A}]^m[\text{B}]^n$. Now if we consider the ...
Chitraksh Pandey's user avatar
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Reason for differences in AChE aging/reactivation kinetics between neutral and charged organophosphorus inhibitors

According to the referenced papers, acetylcholinesterase that has been inhibited by an organophosphate possessing thiocholine as its leaving group is more susceptible to reactivation by oxime ...
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Why doesn't HBr show allylic substitution in presence of Peroxide?

HBr reacts with alkenes such as propene in the presence of Peroxide as per the Anti-Markovnikov rule. This is an addition reaction, forming 1-bromopropane as the major product. This happens due to the ...
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HCN reactor design

For my diploma work, I should design a hydrogen cyanide (HCN) producing reactor. I found that for the BMA process, overall $$\ce{CH4 + NH3 -> HCN + 3 H2 \quad{} \Delta{}H_r = \pu{251 kJ / mol} }$$ ...
Laman Alipashayeva's user avatar
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2 answers
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Can glycerol slow down the kinetics of an inhibitor going to a binding pocket of a target enzyme?

I am currently doing enzymatic inhibition assays and in my current setup I observe that a commercial inhibitor is showing inhibition as expected. Still, the inhibition is not as strong as the ...
raptorlane's user avatar
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Does the E1cb elimination mechanism have a first-order or a pseudo-first order rate law?

Elimination reactions turning a single C-C bond into a double bond are classified as E1, E2, or E1cb, depending on the mechanism (concerted or with intermediate), the stereochemical outcome and their ...
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Does pH affect the activation energy of decomposition of hydrogen peroxide using iron (III) nitrate solution?

I know that pH can affect the activation energy of the decomposition of hydrogen peroxide when catalase is used, as catalase is an enzyme. However, if I use some nonenzymatic catalysts like iron (III) ...
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A first order gaseous reaction - getting the rate law

There is a specific example cited in our NCERT Class 12 textbook, to find out the rate law equation for a general gaseous reaction, $$\ce{A->B + C}$$ It describes the entire procedure as shown: ...
Harikrishnan M's user avatar
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NaOH etching time and temperature for Stainless Steels (SS-304) for Surface Preparation for coating

To improve adhesion of TiO2 coatings on stainless steel sample I am treating SS-304 with 1M NaOH for functionalizing the surface with metal hydroxide groups as well as increasing roughness. What would ...
Shah Fuhaid's user avatar
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Is my derivation for the reaction orders of a single-step reaction valid?

Recently in my chemistry class I learned about reaction orders. For some reaction $\ce{r_1A1}+\ce{r_2A2}+\dots+\ce{r_nA_n}\rightarrow\ce{B}$, $m_1,\dots{,m_n}$ are the orders of that reaction. The ...
Eyeballer's user avatar
4 votes
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Activation energy depends on the form of the rate law

I was going through the following example, on p. 73, in a textbook called Chemical Reaction Engineering (3rd ed.) by Octave Levenspiel: Experimental studies of a specific decomposition of A in a ...
Tan Yong Boon's user avatar
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Why is my Briggs-Rauscher reaction not oscillating?

I have been trying to run the Briggs-Rauscher reaction following this guide, which is pretty similar to other guides out there, yet the reaction is failing to not only oscillate, but display any color ...
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Model EC50/Kd values using ordinary differential equations

It is my first attempt at using ordinary differential equations to model Kd for antibody binding and help will be much appreciated. To provide some context, I possess binding curve data for the EC50 ...
hypermiler3's user avatar
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How to remove color from bromostyrene/dibromostyrene

Distillation under low heat can remove color (excess bromine) but this is time consuming and there is a danger of bromostyrene polymerization even with added TBC. In aqueous, sodium thiosulphate can ...
Don Volk's user avatar
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Derivation of general binding equation (macromolecule with multiple binding sites)

So the last days I'm stuck at trying to solve the an equation - but I just can't (see the screenshot below. So the idea is that you have a receptor or enzyme with multiple binding sites for a Ligand (...
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Reaction kinetics exercise for hydrogen iodide synthesis

The rate constant for the reaction of hydrogen with iodine is $\pu{2.45E-4 M-1 s-1}$ at 302 °C and $\pu{0.905 M-1 s-1}$ at 508 °C. a. calculate the activation energy and Arrhenius preexponential ...
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1 answer
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First order kinetics

Finding time t in a first order reaction (JEE Adv 2019) In reference to the above question,taking into account the stoichiometric coefficient, the standard equation of first order reaction time ...
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Specific temperature ranges of kinetic combustion mechanisms

Do kinetic combustion mechanisms typically operate within specific temperature ranges? I tested some mechanisms from the scientific literature, and apparently they were only working at temperatures ...
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Thermoplastics crystallization during nonisothermal cooling cycles

I have tested a PAEK family polymer using differential scanning calorimetry (DSC) with heating-cooling-heating cycles under different cooling rates (heating rates remained unchanged). PAEK are semi-...
Rod's user avatar
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Units of Activation Energy

Consider the reaction $$\ce{aA + bB -> cC + dD}$$ whose reactants are given by A and B and the products are C and D. Say the activation energy of this reaction is some $x$ joules/mole, But moles of ...
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1 answer
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Why Michaelis Menten Assumption of equilibrium is necessary to integrate rate of ES production

I read in my textbook that the assumptions of equilibrium and of steady state used by Michaelis and Menten were simplifying assumptions intended to make the following equation one that can be ...
Zak's user avatar
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3 answers
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Why is concentration never zero for zero order reactions? [closed]

By formula of zero order reaction:- $$C_t=C_o-kt$$ The concentration should be zero at $t=C_0/k$. But in some books and websites I saw that graph between concentration and time don't touch the X-axis. ...
NOTE Book's user avatar
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1 answer
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Calculating Fractional Yield as a function of temperature for a parallel reaction in a plug flow model

(This question comes from a Chemical Engineering background, I hope it still falls in the scope of engineering.stackexchange.com If not, please move.) I am trying to calculate and plot fractional ...
Hsauce13's user avatar
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why does rate determining step lead to these inequality relations?

Here, the rate expression for the mechanism (i) is below: $$rate = \frac{K_1^2k_2k_3[H^+][A]^2}{k_{-2}+K_1k_3[A]}$$ and for (ii), $$rate = \frac{K_1k_2k_3[H^+][A]^2}{k_{-2}[H^+]+k_3[A]}$$ I was asked ...
wayrese's user avatar
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What exactly are the stages of the reaction between an oxygen ion and a water molecule?

I found information on the website water.lsbu.ac.uk - Oxygen and water: Between altitudes of $80-\pu{100 km}$, $\ce{O2^{\small{\bullet}+}}$ and $\ce{NO+}$ ions are the dominant cationic species. $\ce{...
Wojciech's user avatar
1 vote
1 answer
58 views

Explain estimating intercellular fluxes

Formula that I am using to calculate intercellular fluxes: $$ J = \frac{4D}{\pi d} \big([C]_1 - [C]_2\big), $$ where the flux through a hole is $d$ of a solute with a diffusion coefficient $D$ that is ...
user137376's user avatar
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Equilibrium constant of the formation of ferric thiocyanate

I was reading the paper Relaxation Kinetics of Ferric Thiocyanate (Goodall et. al, 1972) and I came across a passage which read $\space$ Reaction (1) is the simplest representation of the equilibrium ...
Cold_Spaghetti's user avatar
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303 views

Derivation of the Van 't Hoff equation

I was reading the paper Relaxation Kinetics of Ferric Thiocyanate (Goodall et. al, 1972) and I came across the passage Reaction (1) is the simplest representation of the equilibrium between ferric ...
Cold_Spaghetti's user avatar
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Is preferential oxidation/reduction at electrodes only dependent on the reduction potential or is it also dependent on kinetics?

It is commonly taught that in electrochemical cells where there are 2 different chemical species that can be oxidised/reduced, species with more positive actual reduction potentials (concentration ...
Heat's user avatar
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Alleged temperature dependance of activation energy?

According to Master Organic Chemistry (https://www.masterorganicchemistry.com/2012/09/10/elimination-reactions-are-favored-by-heat/), in point number four, the activation energy for a reaction is ...
xasthor's user avatar
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2 votes
2 answers
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Can Spectator Ions Affect Reaction Kinetics?

Specifically, I am interested in the reaction of different hydroxides (in aqueous form) with $\ce{CO_2}$. I would like to determine which hydroxide would conduct the reaction the fastest. My initial ...
jb0's user avatar
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3 votes
1 answer
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Effect of presence of competitive inhibitor on observed reaction constant

Suppose there is a solution of enzyme, its substrate, a competitive inhibitor, and a suicide inhibitor. The reaction rate constant for the reaction of the suicide inhibitor with the enzyme is known. ...
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4 votes
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Concentration units for kinetic mechanism of combustion

I am reading Tamás Turányi & Alison S. Tomlin's Analysis of Kinetic Reaction Mechanisms (2015). On page 10-11, the authors state that for a mechanism with $N_R$ reactions involving $N_S$ species, ...
math_lover0105's user avatar
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What is the reaction between crystal violet and bleach (sodium hypochlorite) and what is the mechanism of its action against crystal violet?

I'm trying to find the reaction between bleach (sodium hypochlorite) and crystal violet, and need to find the mechanism of its action, as during my lab investigation the bleach did cause the crystal ...
konoton's user avatar
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7 votes
2 answers
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Does stoichiometry matter in extent of reaction calculation?

I was recently introduced to the extent of reaction and learned that it can be calculated using this equation $$\xi = \frac{n_{A,out}-n_{A,in}}{\nu_A}.$$ If I'm using this formula to calculate the ...
Leon's user avatar
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Gibbs free energy of transition and activation energy

Let's consider a reaction A (reactant) -> B(product) and activated complex is denoted by C. This graph ( potential energy vs reaction coordinate ) tells us that reactant need some amount of ...
Bharat Prajapat's user avatar
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1 answer
122 views

Is half-life defined for a reaction or for a reactant?

Consider the following chemical reaction. $$\ce{A + B -> Products}$$ If this is a zero-order reaction with respect to $\ce{A}$ and $\ce{B}$, then is there a half-time for this reaction? Or must we ...
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