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

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Deriving kinetic equations for a complex reaction system

I have a system of protein reactions that I've derived differential equations for the kinetics of. I'm using them to run simulations to fit the rate parameters, but the simulations at present are ...
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54 views

The effect of reactant concentration on when equilibrium is established

Take the equation $$\ce{A(g) <=> B(g)}$$ where the reaction is first order with respect to A. The rate law is thus $$\frac{\mathrm d[\ce{A}]}{\mathrm dt}=-k[\ce{A}]$$ Say you run the reaction, ...
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8 views

Effect of His-tag on enzyme activity

In my biochemistry laboratory class, I designed an experiment to study the effect of a His-tag on enzyme activity. First, I measured the activity of the His-tagged enzyme. Then, I cut off the His-tag ...
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1answer
41 views

How does changing the concentrations of intermediate products/reactants change the rate law?

A = CH2(CN)2 B = CH(CN)2- C = BrCH(CN)2 The rate law above is derived from applying the steady state approximation. I am trying to work out how to modify the rate law to accomodate the following ...
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16 views

Factoring in kinetic equations [duplicate]

The mechanism for the linear chain reaction of H2+Br2 -> HBr is: If we presume steady state for the chain carrier Br*, we recieve this equation: My question is in regards to the '2' factor marked ...
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12 views

In Statistical Transition State Theory, why is $[AB^{\ddagger}_f] = [AB^{\ddagger}_r]$?

For example on Wikipedia (https://en.wikipedia.org/wiki/Transition_state_theory), and also in my lecture notes, it is assumed that for a reaction $A+B\rightleftharpoons AB^{\ddagger} ...
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19 views

How can we integrate Maxwell-Boltzmann's distribution to obtain the expression for activation energy?

I tried integrating the expression first by replacing the v^2 terms by E. It turned out to be the integral of (sqrt.E * e^(-E/kT)). I tried integrating it by parts but the exponential term will ...
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32 views

“Reacts most vigorously”

What is meaning of "Reacts most Vigorously" Is it related to Thermodynamic aspect or Kinetic? Like for example if we are given that A reacts with C more vigorously than B reacts with C. Then which ...
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24 views

Which reactions are more temperature sensitive, the ones with higher Ea or the ones with lower Ea and why?

I wasn't able to find much useful content on googling it, however on doing the math i came to a conclusion that the ones with higher Ea are more sensitive to increase in temperature. But why is it so? ...
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14 views

Halving the electrolyte concentrations of a voltaic cell

Say you have a standard voltaic cell with $Q=1$. The concentrations of both the electrolytes are at 1.0 M. If you halve the concentrations in both to 0.5 M, $Q$ still equals 1 and ...
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80 views

Is the rate determining step the step with the largest Ea?

I've seen some controversy on this question while doing a brief search. For example, this SE answer quotes Wikipedia and says that the RDS is the step with the largest $E_a$. However, this UC Davis ...
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19 views

Looking for solubility kinetics of zinc chloride hydroxide monohydrate

$\ce{Zn5(OH)8Cl2·H2O}$ is a crystalline solid insoluble in water. Often used as nutritional supplement. Preparation and chemistry of zinc chloride hydroxide monohydrate is known. I am looking for some ...
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2answers
357 views

How does an energy input actually change a molecule?

I'm reading an online biochemistry textbook for fun, and a question that has bothered me on chemistry before popped up again. The question here is not specific for the chemical process described, but ...
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1answer
39 views

Experimentally finding order of a reaction

For the reaction of bromocresol green and bleach, I was supposed to conduct an experiment to find the order of the reaction with respect to bleach. To do this, I used a fixed amount of bromocresol ...
2
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0answers
18 views

Binding Energy and Enzyme Rate

I was preparing for the Canadian Chemistry Olympiad and I ran into the following question on one of the past exams: If enzyme A binds to the substrate 25 times stronger than enzyme B, what is the ...
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9 views

How to calculate the rate of micelle formation in a soap solution?

How can I design and conduct an experiment to calculate the rate of micelle formation in a soap solution? This would relate to the topic of chemical kinetics which we are currently doing in class.
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29 views

falling ice from balcony [duplicate]

i was wondering Would dropping an ice cube that is 1 inch by 1 inch and 1 centimeter thick from 11 stories or higher do anything if it hits a person or a car? Also if it is melting does that make a ...
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1answer
77 views

What does a fractional order of reaction mean for the mechanism?

I'm doing a high school/sixth form college investigation of the kinetics between magnesium ribbon and hydrochloric acid. I have obtained a rate order was 1.5 w.r.t [H+] and hence the rate equation ...
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13 views

kinetics of adsorption of hydrogen on nickel

What is the order of reaction involving adsorption of Hydrogen on Nickel? The reaction does not depend on the concentration of hydrogen (does it?) but depends on the surface area of nickel. More the ...
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60 views

Why is 2H2O2 -> 2H2O + O2 a first order reaction?

My book says that the reaction $\ce{2H_2O_2 -> 2H_2O + O_2}$ is a first order reaction and that it's rate equation is $\ce{k[H_2O_2][I^{-}]}$. However i don't see why that would be first order? ...
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15 views

Measuring reaction rates when reactants and products both have (different) molar extinctions at the chosen wavelenghth

In my Biochem labs we would always measure the consumption of NADH, and they always noted that it was useful that NAD+ had essentially no absorbance at 340 nm, which allowed us to directly relate ...
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1answer
25 views

Bimolecular and Isomerization reactions

Is it possible to describe a reaction of the $$\ce{A + B <=> AB}$$ exactly using the solution of an isomerization reaction? $$\ce{A <=> B}$$ I just can not figure it out the equations ...
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1answer
43 views

How to calculate the rate of reaction of Sodium and Chlorine

$$\ce{2Na(s) + Cl2(g) -> 2NaCl(s)}$$ How exactly do you calculate the reaction rate of the following equation? Since reaction rate is usually calculated in moles per $\rm dm^3$ per second ...
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61 views

Factors affecting mass of a gas-evolving reaction mixture over time

Excess magnesium was added to a beaker of aqueous hydrochloric acid on a balance. A graph of the mass of the beaker and contents was plotted against time (line 1). What change in the experiment ...
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41 views

Questions about Collision Theory [closed]

The collision theory states that, for a reaction to occur, particles must collide with each other. How about a reaction that has only 1 reactant, for instance decomposition of water / hydrogen ...
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21 views

Kinetics: Rate and Order of Reaction

I have run a reaction of 0.020M $\small\ce{FeCl3}$ and 0.020M $\small\ce{KI}$. The solvent of $\small\ce{FeCl3}$ was $\small\ce{HCl}$, but had no effect on the reaction and, therefore, has a reaction ...
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1answer
25 views

finding the concentration of B

At the intersection point of two curves nA-->mB, the concentration of B can be given as:(assume the reaction to be 1st order) can someone explain me how to go about it? I have no clue how to go ...
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1answer
25 views

Do we use activities or concentrations in the rate expression?

The equilibrium constant of a reaction is a dimensionless quantity due to the fact that we use activities instead of concentrations(in moles/liter). But, in the rate expression for a reaction, do we ...
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22 views

Shape of the blood CO2 dissociation curve

What equation determines the shape of the blood $\ce{CO2}$ dissociation curve? I know that since it factors all possible forms of $\ce{CO2}$ carriage, there are a bunch of factors (e.g. Henry's law, ...
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23 views

Arterial blood CO2 content, division and partial pressure

My lecturer cites Boron and Boulpaep's Medical Physiology (2nd edition) for the following claims: the total $\ce{CO2}$ content of arterial blood is $26.4$ mmol/L or $48\%$ v/v (not sure if these ...
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25 views

Theoretical Value of Activation Energy of Potassium Iodate and Sodium Bisulfite?

I investigated the Arrhenius equation using the reaction between potassium iodate (containing the IO3- iodate ion) and sodium bisulfite (containing the HSO3- hydrogen sulfite ion. The ionic equations ...
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1answer
37 views

Determine rate equations for entire kinetic scheme

I am working with the following kinetic scheme that represents pyrolysis of a biomass particle: The paper that discusses this scheme provides the following rate constants: K1 for the pathway of ...
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1answer
40 views

Comparison of rate of reaction in bromination and chlorination

I did research, about this one but the data and other things prove chlorination is faster than bromination, because chlorine is more reactive. But, some data says reaction of chlorine is more ...
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2answers
67 views

Kinetic isotope effect in nitration of benzene

What is the effect of changing all the hydrogen atoms in benzene to deuterium? For example, which of the following reactions occurs at a faster rate?
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1answer
103 views

Determine reaction rate from reaction time?

These are the results of my experiment (solution A and B were reacted and the reaction time was measured). Data Table Edit: How would I determine the rate of reaction (so I can find the rate law) ...
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25 views

Zinc oxide reduction in ethanol

I'm trying to prepare a ZnO thin film deposited on a glass substrate. The precursor solution prepared by sol gel process through dissolving 1 M zinc acetate dehydrate (ZAH) in ethanol with ...
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1answer
81 views

Determine reaction rate constant from the reaction time?

I was doing some research and I came across an experiment similar to mine (potassium iodate with sodium bisulfite) from the University of Massachusetts ...
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3answers
61 views

Can rate of reaction depend on both the reactants and the product?

In introductory chemical kinetics, an elementary reaction is taken for instance $$\ce{A -> B}$$ Then, we go on to derive integrated rate kinetics equations for them by assuming $$\text{rate} = k ...
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49 views

If chemical reactions occur because everything tends to a lower energy state, why is there such a thing as equilibrium? [duplicate]

It just doesn't make any sense, if a reaction occurs because the reactants go into a lower energy state, then there should be no such thing as equilibrium. right? Because that would mean that the ...
2
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1answer
39 views

How does cooling increase the selectivity of a reaction producing the kinetic vs the thermodynamic product?

I know that cooling gives a lower ratio of molecules with sufficient energy to overcome the activation barrier, but I'm not sure how this selects for a kinetic or thermodynamic product. I also know ...
3
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1answer
56 views

Sodium thiosulfate and Hydrochloric acid

If I was using this method (http://www.rsc.org/learn-chemistry/wiki/Expt:The_effect_of_concentration_on_reaction_rate) however used pre-prepared concentrations of sodium thiosulfate solution, which ...
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45 views

How can I determine the activation energy of a reaction if the reaction rate constant is unknown?

I am trying to conduct an experiment to determine the activation energy of the following chemical reaction: $$\ce{IO3- (aq) + 3HSO3- (aq) -> I- (aq) + 3SO4^2- (aq) + 3H+ (aq)}$$ $$\ce{5I- (aq) + ...
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1answer
39 views

Where does the rate equation come from? (r = k [A]^x [B]^y)

Equations are great, but they're much better when you can understand them. I don't quite get why this works. Could someone explain it to me?r = k [A]^x [B]^y
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How to calculate the rate constant for the reaction of mercury chloride and oxalate?

If for the reaction $$\ce{2HgCl2 (aq) + C2O4^2- (aq) -> 2Cl^- (aq) + 2CO2 (g) + Hg2Cl2 (s)}$$ The initial concentration of $\ce{HgCl2}$ is $0.0836~\mathrm{M}$ (first order), of $\ce{C2O4^2-}$ is ...
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77 views

Kinetics lab (Iodine clock experiment)

I did a lab, an kinetics lab (iodide clock) and in my lab report I have to calculate the initial rate in $\ce{mol ~l^{-1} ~s^{-1}}$ and I'm not sure how to do that. I have the $\ce{[I^{-}]}$ and ...
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Relation between Gibbs energy and net reaction rate

I have come across some papers in biochemistry that seem to claim that a reaction can be "near equilibrium" even though the flux through the reaction (net reaction rate) is large. For example, this ...
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Rate of Fenton Reaction

I want to determine rate of Fenton reaction with different concentration of $\ce{Fe^2+}$. These are some questions that I have encountered: How long does it usually take for the reaction to ...
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42 views

Lab, rate law, finding Keq, question about determining number for Rxn order. Round to 1? Or not?

For a lab experiment I did, I'm calculating the reaction order for one of the reactants using data from two trials, both rates and the concentration of that reactant during each. ...
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1answer
70 views

What happens to the lost mass in radioactive decay?

We were studying kinetics in class which led me to wonder what happens to the decayed matter. After all, there is a loss in mass and according to mass energy equivalence, there should be some release ...
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26 views

What are some technologies/biosensors for real time kinetic analysis of reactions? [closed]

I am in a lab that has used surface plasmon resonance (SPR) and ELISA very heavily over the past few years, and we are thinking of getting a new machine. I'm wondering what other technologies exist ...