The study of rates of chemical processes.

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Multiplication of the reaction and Equilibrium constant

$$\ce{2A + 2B -> 2C }\\ \ce{A + B -> C}$$ Why does the equilibrium constant change? And why the rate of the first reaction square the rate of the second? I understand it mathematically, but ...
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Rate Constant Units and Eyring Equation

Rearranging the Eyring equation leads to the following: $$ ∆^\ddagger S^\circ = R \ln{\frac{k \times h}{{k_B}{T}}}+\frac{∆^\ddagger H^\circ}{T} $$ where k is the rate constant, h is the Planck ...
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17 views

Is the end of a cigarette on fire when lit?

Is the end of a cigarette on fire when it is lit? Or is it smoldering? Is there a chemical difference between the two?
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Simple Kinetics Clarification

I just wanted to check my understanding of this. Given the reaction, $$ (1) \; \ce{A->B} $$ the corresponding rate law is $ v=k[A] $ Also consider $$ (2) \; \ce{A <=> B} $$ with forward ...
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61 views

Deriving goldman equation

So I've been trying to follow the derivation of the Goldman-Hodgkin-Katz equation on Wikipedia (https://en.wikipedia.org/w/index.php?title=Goldman_equation ) - I can follow it through after it sets up ...
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42 views

Can an excessive reactant amount result in a longer reaction time?

I am performing an experiment with DTZA and Ferrate. After a point of increasing the DTZA concentration too much the Ferrate takes longer (lower reaction rate) to react with the DTZA. Is this ...
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33 views

The effect of concentration on the rate of a homogenous reaction

I have to do an experiment where I will find out what the influence of the concentration on the reactionspeed of a homogenous reaction is. We are asked to create 2 solutions, respectively A and B: ...
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290 views

What are some good examples of rate equations for a math class?

I'm a mathematician who's currently teaching a course on differential equations. Though I don't know much about chemistry, I like to include examples from chemistry in my course, and I prefer for the ...
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rate determination by 1H NMR spectroscopy

Currently I investigate a reaction where a starting material A reacts with an excess of thiophenol B towards products C and D. As shown by recurrent TLC analysis of the reaction, the formation of D ...
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25 views

Reaction Rate Limiting Reaction

Why exactly does the slowest reaction limit the instantaneous rate of a reaction even if the faster processes come after? Theoretically, if the products of the slow reaction are required for the fast ...
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44 views

Specific Case of the Rate law

My textbook says that for a chemical reaction with two reactants, $\ce{A}$ and $\ce{B}$ with equation $\ce{aA + bB -> Products}$, where $a$ and $b$ are coefficients, the general rate law is: ...
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Deriving the Rate Law

How do you derive the formula for the general rate law? Where does it come from, and why? I know how to use them and get information from them, but not why they are correct. Do they follow from the ...
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79 views

Reaction Order Greater than 1

What is the chemistry behind why reactions of order >1 exist? And what role does the number of activated complexes formed have in determining reaction rate?
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Temperature in the Maxwell-Boltzmann Distribution

I am attempting to generate the probability for the specific speed of a molecule using the Maxwell-Boltzmann distribution, but I cannot decide on which temperature I should use in the equation. For ...
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226 views

Calculate the specific rate constant (k)

The question is: Suppose we found that the reaction of Red#3 with bleach is 1st order in hypochlorite. The observed rate constant ($k_{obs}$) for one of the trials was measured to be $0.00400 ...
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203 views

Finding the average rate of consumption

The question is: If $2.0 \cdot 10^{-4}$ moles of dye in $50$ mL of solution is consumed in 188 seconds, what is the average rate of consumption of dye in $\text{mol}/\text{L}\cdot \text{s}$? I am not ...
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27 views

Evaporation velocity of ethanol: adding ethanol vapour to a gas mixture

I need to add a known amount of ethanol vapour to a gas mixture (He/Ar). To do that I let the mixture bubble in liquid ethanol kept at a known temperature (14 C). The system is made of a large steel ...
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45 views

Determining order of a reaction without isolation

I'm writing a computer program to calculate the order of a chemical reaction with respect to each reactant. When I do this by hand, it's easy to isolate which reactant concentration stays relatively ...
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48 views

Which of the these SN1 solvolysis of two alkenyl bromides reactions is faster?

The SN1 solvolysis of one of the following alkenyl bromides is in MeOH approximately 100000 times faster than the other one. Which is the more reactive one? Draw the mechanism including the ...
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62 views

How do I calculate the order of a reaction given slope?

I'm an AP Chemistry student, and we're doing the Decomposition of H2O2 lab, in which we decompose H2O2 with KI as a catalyst. I've gotten this data so far: ...
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45 views

How to calculate the frequency of cyclohexane conformational interconversion?

My book mentioned that the energy barrier for cyclohexane to reach the half-chair conformation is 50.6 $\text{kJ mol}^{-1}$. It says that from this value, it was calculated that cyclohexane undergoes ...
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255 views

How can molecularity be the order of the rate determining step?

In my textbook the molecularity is defined as(along with the standard definition) the order of the rate determining step(RDS). It is also given that the order can be a fraction but molecularity is ...
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36 views

Question concerning the scaling for % completion time in a Michaelis–Menten scenario as a function of substrate concentration

Say I have a straightforward Michaelis-Menten reaction where an enzyme $E$ at some fixed concentration $[E]$ forms an interaction complex $ES$ with a substrate $S$ (with initial concentration ...
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How to estimate reaction products of competitive binding?

I have an two reactions, $A + C \rightleftharpoons AC$ $B + C \rightleftharpoons BC$ I'd like to estimate relative steady state proportions $\frac{[BC]_{SS}}{[AC]_{SS}+[BC]_{SS}}$ and ...
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Hill constant cooperativity

Is there an expression for calculating $K_d$ for a cooperative system (using the Hill constant)? I can't find one online and there was none given in my lectures, only a rearranged formula for the ...
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120 views

Is there a general consensus on the causes of the $\alpha$-effect?

There have been various explanations posited for the $\alpha$-effect. It is currently in the list of unsolved problems in chemistry on Wikipedia, but, due to a lack of references to that effect, I'm ...
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Langmuir Adsorption

So I recently ran into the topic of adsorption onto Langmuir surfaces. So let [S] be the concentration of sites without anything bound to them [A*] be the concentration of A and site pairings and [S]0 ...
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124 views

Speed of ionic reactions?

Why are ionic reactions extremely fast, as compared to other gaseous reactions? The ionic reactions (precipitations, neutralizations etc.) are extremely fast (somewhere about $10^{12}$ times ...
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179 views

Why are tertiary alkyl halides obtained as major yield than secondary or primary during free radical halogenation of alkanes?

Halogens ($Cl_2$ and $Br_2$ ) react with alkanes in the presence of ultraviolet light to form haloalkanes.This reeaction is free radical substitution and gives a mixture of mono, di or ...
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371 views

Why is the reactivity of primary alkyl halides with nucleophiles ($S_N2$ mechanism) is greater than secondary and tertiary alkyl halides?

For the reaction between alkyl halide and a nucleophile, following the $S_N2$ mechanism, the reacitivity of alkyl halides is in the order: $$primary\ halide > secondary\ halide > tertiary\ ...
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1k views

How does the Inductive effect, explain the reactivity of alcohols with halogen acids?

The reactions of primary and secondary alcohols with halogen acids ($HX$, where $X$=halogen) require the presence of a catalyst, $ZnCl_2$. With tertiary alcohols, the reaction is conducted by simply ...
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What is the difference between ZCT Tunneling correction and Wigner Tunnelig correction in computational Quantum Chemistry?

I've been doing some computational calculations about kinect rates of a reaction and I was told to perform both ZCT and Wigner corrections to calculate these rates. But I don't know the difference ...
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111 views

Activation energy clarification

This is probably a very small clarification I seek, but it has been bothering me from quite a while. In the Arrhenius rate equation $$k=Ae^{-\frac{E_a}{RT}}$$ (where $E_a$ is the Activation energy), ...
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Find the unit of Rate Constant?

Consider the reaction, $\ce{2A + B -> Products}$. When concentration of B alone was doubled, half life did not changed. When concentration of A alone was doubled, the rate increased by two times. ...
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How can I go about obtaining the activation enthalpy of a reaction using the Arrhenius Equation experimentally?

I plan to do a string of experiments on the kinetics of the decomposition of hydrogen peroxide. I'm going to see the effect of catalyst concentration on rate and the effect of varying hydrogen ...
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214 views

How is it that the equilibrium constant does not depend on mechanism?

For a reaction, $$aA+bB \rightarrow cC+dD$$ The equilibrium constant is $$k_c=\frac{[C]^c[D]^d}{[A]^a[B]^b}$$ Regardless of the mechanism of the reaction. Why is this the case? EDIT: I've seen ...
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Does the hydrolysis speed increase when more H+ ions are in the solution?

Does the hydrolysis speed increase when more $\ce{H+}$ ions are in the solution? So if I were to use $\ce{H2SO4}$ instead of $\ce{HCl}$ (same volumes) then $\ce{H2SO4}$ will be the most effective?
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How does initial rate of reaction imply rate of reaction at any time?

My textbook begins the Chemical Kinetics section by describing the initial rates method of determining the rate of reaction. I understood it as the following (for a first order reaction): ...
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140 views

Storing kinetic energy in bonds

Let's assume a setup with a static linear molecule with three identical atoms connected by bonds and a single atom, identical to the other three, being shot at the molecule. Let's also assume that ...
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Analytical solution to first-order rate laws

Does anyone know the analytical solutions to the following rate laws: 1) $\frac{d\rho_W}{dt} = -\rho_W*(K_1+K_2+K_3)$ 2) $\frac{d\rho_T}{dt} = \rho_W*K_2 - (K_4+K_5)*\rho_T$ 3) $\frac{d\rho_C}{dt} ...
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How to calculate the change in the rate of reaction?

Here is the question in my textbook (1) -- If $r = k[A]_0^2[B]_0^1$ for a reaction, by what factor is the initial rate multiplied if the $[A]_0$ is multiplied by $1.5$ and the $[B]_0$ is ...
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How should I modify my molecular dynamics simulation so that known chemical reactions can be modelled?

I have written some molecular dynamics code that I want to use to model known chemical reactions. By known I mean that it has been observed in a lab that $\ce{A +B->C}$. I am not interested in ...
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59 views

What is the reaction order of a reaction?

Here's is what I understand so far and the following is referenced directly from UNSW CHEM1061 lecture notes by Professor Pall Thordarson: order of the reaction SHOULD be equal to the number of ...
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51 views

What does an endpoint saturated signal mean. How does it relate to equilibrium constant?

I have had a question that has been bugging me for a couple of years in my graduate school career, and I was wondering if perhaps someone could help explain it to me. Given an endpoint assay like this ...
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Integrated rate law graphs

Why does the graph of $ln[A]$ vs $t$ produce a straight line for the first order rate law? Also why does the graph of $t$ vs $\frac{1}{B}$ produce a straight line for the second order rate law?
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Estimating Surface Reactions - Liquid, Turbulent Flow

So, I need a method of estimating the influence of a surface (rate constant would do for a start), the idea is to estimate just Reactant + Surface -> Product in a turbulent liquid flow. Now I am ...
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154 views

Michaelis Menten Deriviation for 2 Enzyme Substrates

We know that the Michaelis Menten derivation for the following reaction: $\ce{E + S \rightleftharpoons ES -> E + P}$ Howver, what if the reaction took place in a different scenario whereby: ...
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Question Regarding the Chlorine Dioxide-Iodine-Malonic Acid Reaction

After reading a section on this particular oscillatory reaction, something started bugging me about it. However, let me lay out the basis of my question. From what I've researched, Lengyel and ...
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108 views

Iodine clock with moving bands

Has anyone seen a version of the iodine clock reaction where instead of the system oscillating between clear and blue it shows blue bands travelling down the vessel? I ask because someone not unknown ...
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443 views

Application of the Arrhenius equation to a parallel reaction

I'm struggling with this homework question: "For a parallel reaction A goes to B with rate constant $k_1$ and A goes to C with rate constant $k_2$, you determine that the activation energies are 71.9 ...