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

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Rate Kinetics(suggested mechanisms)-Chemistry [on hold]

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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Error in Mathematics of Collision Theory [migrated]

I'm making lecture notes, and I felt that it would be important to explain some of the math behind collision theory. I come up with a problem, however. Here, I'm trying to show that the collision of ...
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2answers
55 views

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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26 views

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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49 views

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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19 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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1answer
33 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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27 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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43 views

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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28 views

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 ...
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34 views

Suggest a method, other than spectrophotometry, for determining the reaction rate

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 were used to determine the rate law and the ...
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28 views

Which species can't appear in the rate expression for this reaction scheme?

The answers are apparently F and G, but I don't see why D and E couldn't also be valid (considering the first step is the slowest). A and B will inevitably be in the rate equation since they are ...
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20 views

Kinetics where RDS is step 1

Hello, In this kinetics problem Im stuck on how to make my answer simplify to the one given in the question. In this particular part I don't think we use a steady state approximation as there is a ...
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39 views

What is the rate of analysis of hydrogen peroxide?

I'm kind of stuck on this problem: What is the rate of analysis of hydrogen peroxide, if the molar concentration of hydrogen peroxide decreased from $0.85~\mathrm{mol\cdot{}dm^{-3}}$ to ...
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1answer
88 views

Representing woody biomass concentration for kinetic reactions

Woody biomass is composed of cellulose, hemicellulose, and lignin components. The following diagram provides representative formulas for each component: Biomass can be represented by it's density, ...
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47 views

Integration of the first order rate equation

Given the simple first order reaction $\ce{A -> P}$ derive the integrated rate law. $$\frac{d[A]}{dt} = -k[A]$$ Collect terms: $$\frac{d[A]}{[A]} = -kdt$$ Now for the bit I need help with, the ...
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93 views

Experimental difficulty with the iodine clock reaction

I did the iodine clock reaction using sodium metabisulfite and potassium iodate. As I understand it, increasing concentration is supposed to speed up your reaction rate. I did 10 trials. The first 5 I ...
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1answer
91 views

Relative energies between reactants and products

I've been asked to draw a relative energy sketch of the reactants and the two products. The reaction being examined was adding copper acetate monohydrate to glycine in two different fashions to create ...
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1answer
23 views

Sequential Kinetics

I was solving some problems on chemical kinetics, then I was just struck at some ques of sequential reaction kinetics. Given reactions $$\ce{O_3 + Cl \rightarrow O_2 + ClO ~~~ k_1=5.2 \times ...
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1answer
54 views

Calculate species concentration from first-order kinetic reactions

I am trying to determine the concentration of products from the kinetic reactions of wood pyrolysis. The kinetic scheme separates the wood into cellulose, hemicellulose, and lignin. For example, the ...
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1answer
41 views

How does a catalyst affect the rate equation

If I determine the order of the reactants in a reaction without using a catalyst, and then use a catalyst, will the order of the reactants then be different?
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43 views

Is there a list of known rate laws for reactions?

I've been scouring the web for a website/pdf that lists reactions and their corresponding rate laws. Something like: \begin{align} \ce{A + B &-> C} & ...
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14 views

Convert kinetic rate constant into a rate?

Can anyone tell me how I can convert a rate constant derived from first order kinetics (units are hr^-1) into an actual rate (turnovers/hr)? The scenario is that I know my rate constant for a ...
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1answer
45 views

Kinetics: Order of Reaction

I am confused as to how an order of a reactant (n or m) in the rate law can be negative. This means that increasing the concentration of a reactant would actually decrease its rate of disappearance. ...
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1answer
115 views

Conc. vs Time Graph for Second Order Reaction

From my understanding plotting the conc. over time for a 0-order reaction yield a negative linear slope. Plotting conc vs time for a first order reaction intuitively yields an exponential type slope. ...
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1answer
34 views

Finding molarities of individual reagents given the chemical equation and total concentration in a container

I am given a table that gives me the different total pressures at certain times. The decomposition of phosphine is the reaction: $$\ce{4 PH3(g) <=> P4(g) + 6 H2(g)}$$ The time/pressure ...
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How to Determine the Rate Law knowing time and concentrations

Consider the hypothetical reaction described by the following equation: $$\ce{3 A + 2 B -> C}$$ Reagent B was added in excess and the following time concentration data was obtained. ...
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1answer
28 views

kinetic and thermodynamic parameters of biodiesel production from lard

I want to know if someone has experimental results and calculations of the kinetic and thermodynamic parameters of Base Catalyzed Transesterification of pig fat, if not which is the method used to ...
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1answer
72 views

Pseudo 1st order Kinetic reaction

The pseudo 1st order reaction happens when one of the reactant is in large excess and its concentration doesnt change during the reaction . Is there any other such situation when a certain higher ...
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2answers
57 views

How is the rate of a reaction defined?

I have learnt for many years that rate of reaction is the rate of change of concentration of a reactant or product with respect to time. I never questioned this before, but recently I have been ...
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3answers
84 views

Kinetics vs Thermodynamics

The way kinetics is taught at the undergraduate level (Arrhenius and collision theory) chemical equilibrium is determined governed immensely by activation energy of the reaction. According to ...
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1answer
40 views

Is it possible to derive integrated rate law algebraically?

Here is the calculus way: I have no prior knowledge of calculus. But my teacher asks me to derive the integrated rate law for any order between one to ten. It would be fine for me to memorize the ...
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How does an ice bath change the rate of an reaction?

If I had hydrogen peroxide decompose with the help of manganese dioxide and measured the time taken for the reaction to complete and the volume of oxygen collected. I will get a graph that looks like ...
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1answer
18 views

Oxide surfaces develop a charge in H2O. Do we have any, even vague, handle on how long does an indivdual charge last on avg. before being neutralised?

We often know, from e.g. titration experiments, what the average surface charge density of a surface is. How do these charges vary over both time and space (i.e. dynamics)? I have been unable to find ...
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47 views

Reaction Kinetics and Stoichiometry — Mass conservation

This question has been bothering me for some time, and I can't seem to find a good answer online. Say I have four chemical species $\ce{A}$, $\ce{B}$, $\ce{C}$, $\ce{D}$, and these four react in the ...
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2answers
38 views

Predicting rate equations from data

I am having trouble wit the following question on my problem sheet: "The reaction $\ce{Br- + ClO^- \to BrO^- + Cl^-}$ occurs with a rate constant of $\text{0.35 dm}^3 \text{mol}^{-1} \text{s}^{-1}$ ...
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48 views

Second order reaction half life equation?

For the reaction: $$2A\to p$$ The rate, $v$ may be given as: $$v=-\frac12\frac{d[A]}{dt}=k[A]^2$$ Correct? Integrating this gives: $$-\frac12\int_{[A]_0}^{[A]}\frac{d[A]}{[A]^2}=k\int_0^tdt$$ ...
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How to make sense of the 'Relaxation Method' for measuring reaction kinetics?

I get the concept that one can measure the rate of reaction by measuring the rate at which an equilibrium state reaches another equilibrium state after the system is perturbed (usually by heating). ...
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1answer
80 views

Is there a name for the intersection of the graphs of first and second order reactions?

Is there a name for the point where a first order rate of reaction meets a second order one. This point highlighted above.
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1answer
44 views

How is the Rate Law of a reaction measured?

What is Rate Law of the reaction below?$$\ce{4 HBr + O2 -> 2 H2O + 2 Br2}$$ How do we approach finding the rate law of reaction? Can this be found out only through experiments?
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291 views

Why is the rate of disappearance negative?

Rate of disappearance is given as $-\frac{\Delta [A]}{\Delta t}$ where A is a reactant. However, using this formula, the rate of disappearance cannot be negative. $\Delta [A]$ will be negative, as ...
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61 views

Why is it not possible to determine the rate constant this way?

The following equation can be used to determine the rate: $Rate = \frac{-\Delta [A]}{\Delta t}$ This equation can also be used: $Rate = k[A]$ By simple substitution, $\frac{-\Delta [A]}{\Delta t} = ...
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83 views

In the elementary steps of a reaction, why do we assume that the coefficients of a reactant corresponds to its order?

Recently, I was taught that the coefficients of the reactants in an elementary step of a reaction indicates that reactant's order. Why is this the case? I thought that the order of a reactant was not ...
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3answers
614 views

Why is the units of kcat 1/s?

I understand that $k_\text{cat}$ measures the turnover number of an enzyme. This measure is therefore a quantity of molecule conversions per unit of time. I suspect that my problem is more that of a ...
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1answer
26 views

What are the possible concentration pathways for a 3-species system?

Inspired by this question, which asks if a multi-species system could oscillate around its equilibrium, I thought about the possible concentration pathways the following more narrow specified system ...
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339 views

How to solve an Arrhenius equation problem?

A widely used rule-of-thumb for the temperature dependence of a reaction rate is that a ten degree rise in the temperature approximately doubles the rate. This is not generally true, especially when a ...
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Does product induced poisoning qualify as a rate limiting step?

I have a question about whether a particular situation qualifies as a rate limiting step. I have a catalyst that under normal conditions gets poisoned when products accumulate on the catalyst surface. ...
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Stuck with derivation of the integrated rate equation for a pseudo first order equilibrium reaction

I was reading about the integrated rate law. However I have problems to follow the solution. I have an equilibrium reaction: [A]+[B]=[AB] with forward and back reaction. I approximate the ...
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1answer
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Can there be more than one combination of reactant/product concentration for a specific equilibrium constant?

For an elementary reaction like $$\ce{A + B -> AB},$$ $$K_{c} = \frac{\ce{[AB]}}{\ce{[A][B]}}$$ and $$\frac{\mathrm{d}\ce{[AB]}}{\mathrm{d}t} = k\ce{[A][B]}.$$ If I let the reaction reach ...