The study of rates and steps (mechanisms) of chemical processes.

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Reactivity of propellanes

Why is [1.1.1]propellane considerably less reactive than either [2.2.1]propellane or [2.1.1]propellane as illustrated in the hydrogenation reaction below?
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Rate of exothermic/endothermic reactions

Is it necessary that all endothermic reactions be slow and all exothermic reactions fast? This is based on the fact that endothermic reactions require more activation energy than exothermic reactions ...
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How do I find the expiration time of drug in the following example?

An optically active drug has one chiral center and only dextrorotatory isomer is effective. Moreover, it becomes ineffective when original activity is reduced to 35 % of original. The rate constant is ...
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Where can I find simple reaction rate formula for catalytic partial oxidation of methane? [closed]

I have already found equations here but they are too complex (heterogeneous reaction). I need a simplified (and so approximated, limited to such case, but this doesn't matter...) network of equations ...
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Why are rates of reaction faster for ionic compounds than they are for covalent compounds?

Why is it that ionic reactions (i.e., reactions involving ionic compounds) are faster than covalent reactions (reactions involving covalent compounds), even though the ionic bond is stronger than the ...
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48 views

Finding average half life of radioactive nuclide which undergoes two different decays

Find the average life of a radio nuclide which decays by parallel paths $$A\rightarrow B$$ $$2A\rightarrow B$$ where the decay constants are $\lambda_1=0.018\ \mathrm{s}^{-1}$ and $\lambda_2=0.001\ ...
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kinetic reaction rate greater than extent of reaction for equilibrium

I'm comparing a model with chemistry at equilibrium versus a kinetic one. I take a network of two reactions: methane steam reforming (MSR) and water gas shift (WGS) at 700°C. I calculated extent of ...
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64 views

Finding rate of reaction from a concentration vs. time graph

A tangent drawn on “conc. of product vs. time” curve of a 1st order reaction makes an angle 30 degrees with the $y$-axis at 20 min. Find the rate after 20 min. I first tried to find the equation ...
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Belousov-Zhabotinsky reaction: questions about rate determining step, k and activation energy

In one of our lab courses, we performed a variation of the BZ reaction, the experimental procedure is outlined below: Experimental Procedure 10 mL of 3.0 M $\ce{H2SO4}$ was added to test tube T1. ...
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Belousov–Zhabotinsky Reaction

An experiment in my lab was about the Belousov–Zhabotinsky reaction and we measured 2 times - the induction period, which was the amount of time it took for the solution to change color and back for ...
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Is there a way to find the kinetics data for the strong acid weak base reaction?

I am layman of chemistry. Latterly, I am asked to do an mathematical optimization task for a bio-chemical process, which contains a conditioning step to neutralize the sulfuric acid using ammonia ...
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Determine the rate equation (intermediate reaction)

I was helping some students today, quite successfully, until I came across this problem: $$\ce{A <=> B + C}$$$$\ce{C + D \to E}$$ The first equation is a fast process with forward and ...
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Using a modified Arrhenius plot to find activation energy

I have a question on how to determine activation energy from a plot using the Arrhenius equation. I am working as an assistant with general chemistry II students and their lab is the iodination of ...
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76 views

Units in modified Arrhenius equation?

The modified Arrhenius equation is used to express the rate constant in a chemical mechanism model I'm working with. The equations is as follows: $$k_\mathrm{f} = A\times ...
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Why is more of a catalyst added, when it is not consumed?

… catalysis, the acceleration of chemical reactions by substances not consumed in the reactions themselves—substances known as catalysts. (Source) Now as I’ve understood, to keep a reaction ...
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Equilibrium of more than two inter reacting species

We know that equilibrium in a chemical system is attained when forward and backward reaction rates are equal. What if the reaction mixtures involve more than one reaction? For example, consider three ...
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56 views

Effect of Catalysis on Reaction Rate in elementary Reaction

I understand that there are many different catalytic mechanisms that suggest different ways of accounting for the effect of a catalyst on reaction rate. My question is: Given a termolecular ...
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Calculating K Value of a Clock Reaction

Uncertainty Not Included Some Units Not Included R2 value calculated from Header (Concentration, 1 over Concentration and LN Concentration) vs Time Column of ...
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Is the Arrhenius Equation only valid for reactants in the gas state?

I couldn't find a source that explicitly say this, but given the gas constant R is used, is the Arrhenius equation only valid when all reactants are gases? Do they have to be ideal gases? If the ...
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217 views

What is the order of the reaction with respect to NO?

According to a question on my book, The following reaction mechanism has been proposed for the reaction of $\ce{NO}$ with $\ce{Br2}$ to form $\ce{NOBr}$ $$\ce{NO(g) + Br2(g)<=>NOBr2(g)}$$ ...
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58 views

Initial rate of reaction from the graph?

#13 , I tried finding the slope between two points but I keep getting wrong values, how do you find the initial rate? So I started by trying to find a slope of two points. (0,0.4) and (10,0.2) after ...
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59 views

Reaction kinetics, relating half life to reaction rate

How do I relate the half life to the overall rate of reaction? I argued that from the data, doubling the partial pressure of either reactant, keeping the other constant, will half the half life. ...
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Conditions affecting pseudo rate orders

For the reaction: $$\ce{F + Br_2 -> FBr + Br}$$ The gas concentrations as a function of time are given by: $$kt=\ce{\frac{1}{[Br2]_0-[F]_0}}\ce{\ln(\frac{[Br2][F]_0}{[F][Br_2]_0})}$$ Given that ...
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Equilibrium constant in terms of mole fractions

$$\ce{CO + H2O <=> CO2 + H2}$$ A stoichiometric mixture of $\ce{CO(g)}$ and $\ce{H2O(g)}$ is allowed to reach equilibrium. $x$ is the mole fraction of $\ce{H2(g)}$ present. I am meant to ...
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35 views

Computing the concentration of a reactant given formation of products

At high temperatures nitrogen dioxide decomposes into nitrogen oxide and oxygen gas according to $$\ce{2 NO_2 -> 2 NO + O_2}$$ I have a question now. Let's say at a certain temperature I'm given ...
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Computing initial reaction speed given reaction constant

Problem: $\ce{N2O}$ falls apart in oxygen gas and nitrogen gas according to a first order reaction rate. If you know that the rate constant is $0.38\ \mathrm{s^{-1}}$ at $760\ \mathrm{^\circ C}$, ...
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Law of mass action

If you have the forward reaction $$\ce{2X -> P}$$ at rate $K$, would you have $$\frac{\mathrm{d}[\ce{X}]}{\mathrm{d}t} = -2K[\ce{X}]^2,\ \frac{\mathrm{d}[\ce{P}]}{\mathrm{d}t}=K[\ce{X}]^2,$$ or ...
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Unit consistency in rate equations

I suppose that my problem is not one of great profundity, but it is an annoying one. The problem is related to the measurement units involved in rate equations of different order. Not being a chemist ...
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76 views

Predicting incomplete combustion?

I understand the concept of incomplete combustion and that it occurs when oxygen is not a large enough supply to allow for complete combustion. My question is: how can we model combustion properly in ...
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69 views

Why is it the case that KE = 0.5mv^2

To the best of my knowledge, energy equals work, $\mathrm{E = W}$; work equals force multiplied by distance, $\mathrm{W = Fm}$ ; force equals mass multiplied by acceleration, $\mathrm{F = MA}$; and ...
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78 views

Finding 1/V from absorbance in Lineweaver-burk plot

I’ve got six test-tubes with $0.5\ \mathrm{ml}+0.5\ \mathrm{ml}$ of 0.005 %, 0.0025 %, 0.00125 %, 0.000625 %, 0.0003125 % and 0.0003125 % starch and 4.2 pH phosphate buffer solution (2, 4, 8, 16, and ...
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Inferring rate of reaction from time taken [closed]

Can the time taken be used to infer the rate of reaction? Here's an inline link to google
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156 views

Chemical kinetics of a reversible reaction

I am having trouble with the following question: Consider the following reversible reaction in which the reaction is first order in both directions: $$\ce{[A] <=> [B]}$$ $k_a$ is the rate ...
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49 views

Mechanisms in kinetic reactions

In my book is given the mechanism of $\ce{HBr}$ forming and I understand every step of it. We did the calculations of the rate of each reaction, which is easy depending on the sign (-,+) of compounds ...
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115 views

How is the “quasi-steady-state” assumption of Michaelis-Menten kinetics different from the steady state assumption of ordinary kinetics?

In Wikipedia's article for Michaelis-Menten kinetics, it titles the "[ES] = constant" section the "Quasi-steady-state approximation". Lehninger's Principles of Biochemistry, 4th Ed. pp. 203ff call ...
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61 views

Activated complex theory vs. consecutive reactions [duplicate]

Activated complex theory, tells us that due to the collision between the molecules of the reactants, they form a transition specie before the product is formed, which is called active complex. On the ...
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54 views

Order of reactions in kinetics

In kinetics, zero order reactions are those reactions who are independent from the concentration of the reactant or the product. So their rate is equal to the constant k. But still we build the ...
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Importance of unit of time used in rate law problem

If doing a problem where you use the integrated rate law for a second order reaction ($\frac{1}{[\mathrm{A}]}-\frac{1}{[\mathrm{A_0}]}=kt$) to first find $k$, then use that to find the halflife, does ...
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114 views

Activation energy and temperature

It is said that activation energy does not change with temperature. But I am unable to figure out why. If we increase the temperature, the kinetic energy of the molecules will increase and they will ...
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how to depict answer from this graph

i am talking about the 65th question, in the below given uploaded photo, i.e. the first order decomposition curves as per the given reaction for every mole of A3 decomposed, there is a liberation ...
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Rate Kinetics(suggested mechanisms)-Chemistry [closed]

http://maxpapers.com/wp-content/uploads/2012/11/9701_w14_qp_41.pdf question 1C) The compound nitrosyl fluoride, NOF, can be formed by the following reaction. \[\ce{2NO(g) + F2(g) <=> ...
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Why must the rate law be experimentally determined?

I am familiar with the idea that rate law must be determined experimentally. I am also familiar with the idea that there is no formulated way for coming up with the rate law besides just ...
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Find the equilibrium constant

In a container with volume 4 litres we have 2 moles $\ce{COCl2}$ and 4 moles $\ce{Cl2}$. Equilibrium is achieved when 60 % of the reactant $\ce{COCl2}$ is wasted 60 %. What is the equilibrium constant ...
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Given a forward reaction with positive enthalpy, is its reverse reaction be endothermic or exothermic?

I'm pretty sure the sign changes. But, I want to be sure if it becomes endothermic or exothermic.
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42 views

Accelerated Oxidation Of Iron When Coating Breaks

I was presented with the following information: If iron is painted, then oxygen and water are prevented from contacting the metal, and corrosion is avoided. Sometimes the iron is coated with a thin ...
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149 views

How to calculate the temperature at which a reaction becomes spontaneous?

At $25~^\circ\mathrm{C}$, $298~\mathrm{K}$,, the reduction of copper(I) oxide, $ \Delta H = 58.1~\mathrm{kJ}$, $\Delta S= 165~\mathrm{J/K}$, is nonspontaneous, $ \Delta G = 8.9~\mathrm{kJ}$. ...
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106 views

Molar heat of fusion of ice?

The molar heat of fusion of ice is 6.01 kJ/mol. Can you explain what this means? What I think it means is that it requires 6.01 kJ to melt a mole of ice. I'm not positive though..
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Calculate the number of moles of NO₂ (g) produced per hour per liter of air?

A reaction of importance in the formation of smog is that between ozone and nitrogen monoxide described by $\ce{O3(g) + NO(g)->O2(g) + NO2(g)}$ the rate law for this reaction is: rate of ...
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Rate constants for water exchange

Are rate constants for water exchange of transition metal aqua-complexes tabulated anywhere ? I haven't been able to find a resource which is anywhere near comprehensive.
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Justify assuming first-order kinetics for a complex

For the hydrolysis of $\ce{\mathit{trans\hyphen}[Co(en)2Cl2]Cl}$ (and cis) we measured reaction rates via spectrophotometry. Plots of change in absorbance $(\ln(A-A_\infty))$ were used to determine ...