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

learn more… | top users | synonyms

1
vote
1answer
14 views

Kc(equilibrium constant) and Kp

Its given in the book that at 12.18kelvin Kc=Kp. How is that equated from the equation Kp= Kc(RT)^∆ng. I am unable to sort it out, please guide me in to the topic....
1
vote
1answer
48 views

Does the rate function of an elementary reaction depend on the other steps of the mechanism?

A question came to my mind. Is the rate function of an elementary reaction influenced by the other steps of the mechanism? I wonder whether the shape (not the values) of the function $r(c)$ belonging ...
0
votes
0answers
17 views

Order of reaction and stoichiometric coefficient [duplicate]

Why the order of reaction is equal to the sum of stoichiometric coefficient in most cases? And something I found in net: $$\ce{aA + bB → cC + dD}$$ If the above reaction is single-step, then $\ce{...
1
vote
3answers
64 views

Why is the stoichiometric coefficient in the denominator in the rate expression?

For the reaction: $$\ce{2A + B → C}$$ The rate expression is given as: $$\ce{-1/2 * Δ [A]/Δt}$$ = $$\ce{-1 * Δ [B]/Δt}$$ = $$\ce{Δ [C]/Δt}$$ I can't get my head around why it is $$\ce{-1/2 * Δ ...
0
votes
2answers
40 views

What are the order of the reaction under the following conditions?

The experimental rate of a reaction $$\ce{A + 2B -> C + D}$$ $$\frac{\mathrm dx}{\mathrm dt} = K[\ce{A}][\ce{B}]^2$$ Calculate the order of the reaction when (i) $[\ce{A}]\gg[\ce{...
1
vote
1answer
26 views

What guarantees that there is a thermodynamic equilibrium in a closed chemical reaction network independently of the mass-action kinetics? [closed]

I would like to know according to which we can state that there is a unique equilibrium of a closed chemical reaction network (at constant circumstances) without supposing mass-action kinetics if time ...
0
votes
1answer
25 views

How to identify a pseudo first order reaction?

With the integrated rate equation we can easily find out but is there any way of finding when only the reaction is given like, The hydrolysis of acetic anhydride (CH3CO)2O + H2O --> 2CH3COOH a. ...
0
votes
1answer
27 views

Coconut oil vs Olive oil: Spray dynamics

Ps: If this would better fit Physics then please move it there or let me know. I put it here based on fact that viscosity and colloids were part of chemistry curriculum 10/15 yrs back in school. Let'...
0
votes
0answers
45 views

Convert mass-based reaction rate equation to mole-basis

I have the following kinetic scheme describing the conversion of wood to tar and gas products. Wood is considered to be pine with a density of $\rho_\mathrm{w} = 540\; \mathrm{kg/m^3}$, tar is ...
0
votes
1answer
123 views

Explain why alumina-containing zeolites possess chemically active surfaces

I think zeolites possess acid sites that are catalytically active in many hydrocarbon reactions. The pore system only allows molecules that are small enough to enter, hence it affects the selectivity ...
2
votes
1answer
47 views

Calculate the rate of decomposition of H2O2 at 25 °C when [H2O2] is exactly 10.0 mmol/L

I'm really confused? $$\ce{2H2O2 -> 2H2O + O2}$$ $$\begin{array}{ccc}\hline \text{Experiment no.} & c(\ce{H2O2}) & \text{rate} \\ \hline 1 & 14.45 & 3.35 \times 10^{-3}\\ 2 & ...
0
votes
1answer
35 views

Why do coefficients become exponents in the speed equation when dealing with elementary reactions

In school, while studying chemical kinetics, we were learning about the speed law and equation for different chemical reactions. We learned that in general, the exponents of the concentration of ...
0
votes
0answers
17 views

Which class of polymerization reactions reaches high conversion under one second?

Are there polymerization reactions that can reach high conversion very fast, say under 1 sec? i.e. to polymerize "immediately"?
1
vote
0answers
5 views

Parameter effects on kinetics of esterification for bio-diesel production

I want to discuss the effect of parameters on the kinetics of esterification for bio-diesel production. In esterification process, temperature effect and molar ration are two important parameters. ...
3
votes
1answer
65 views

How the equation that describes evolution of alkyl nitrates has been derived?

I was reading this paper, Bertman, S. B., J. M. Roberts, D. D. Parrish, M. P. Buhr, P. D. Goldan, W. C. Kuster, F. C. Fehsenfeld, S. A. Montzka, and H. Westberg (1995), Evolution of alkyl nitrates ...
1
vote
0answers
14 views

Mechanism of thyroid hormone synthesis: iodation and free radical formation

In the synthesis of thyroid hormone, what part of the thyroid peroxidase hormone is specifically responsible for abstracting the free radicals from the aromatic side chains in the iodated tyrosine ...
0
votes
1answer
37 views

Is there are any universal methods or software for reaction rate modelling?

In software like DWSIM are used databanks which contains enthalpy and entropy at 298 K and more other information about chemicals. This software can create a steady-state system, where showed state of ...
0
votes
0answers
22 views

A rate problem;Determining the order

My attempt I believe the answer should be second order reaction looking at the units of k But I think the question is to be solved with the help of integrated laws I tried using it to check ...
-1
votes
1answer
20 views

Rate problem: Determining the order

In the presence of an acid, the initial concentration of cane sugar was reduced from 0.20 to 0.10 molar in 5 hours and from 0.2 to 0.05 molar in 10 hours. What is the order of the reaction My attempt ...
3
votes
1answer
102 views

Problem on chemical kinetics

Is the question asking the concentration when the system has reached its half life Can use the half life formula? The attempt at a solution I used the rate law which I equated to the definition of ...
0
votes
1answer
50 views

Calculating time taken for a set percentage of a reaction to occur based on half-life

The half-life of a first order homogenous gaseous reaction: $\ce{SO2Cl2 -> SO2 + Cl2}$ is 8.0 minutes. How long will it take for the concentration of $\ce{SO2Cl2}$ to be reduced to 1% of the ...
0
votes
0answers
32 views

Latent Heat and Kinetic Energy

The kinetic theory says that temperature is the measure of the average kinetic energy. That would mean then : The temperature rises with the rise in kinetic energy. We know that when matter changes ...
0
votes
0answers
37 views

Elementary Reactions

I'm studying some kinetics of reactions and in particular the topic analyzed is the bromidic acid production starting from $\ce{H2}$ and $\ce{Br2}$. The reaction $$\ce{H2 + Br2 -> 2HBr}$$ can be ...
0
votes
1answer
25 views

Does the Hydrogen/Chlorine reaction in light proceed instantaneously?

When a mixture of Hydrogen and Chlorine is exposed to short wavelength light it reacts explosively. Does the reaction happen simultaneously through the bulk of the mixture?
0
votes
0answers
27 views

potential profile in kinetics and spontaneity in reactions

We usually think of the criterion of spontaneity of a reaction as the change of Gibbs energy. By Clausius inequality, one of various forms of the 2nd law, we know that $ \mathrm{d}S-\frac{\mathrm{d}H}...
2
votes
1answer
40 views

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 ...
3
votes
1answer
61 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, ...
1
vote
0answers
13 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 (...
0
votes
1answer
42 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 ...
0
votes
0answers
18 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 ...
1
vote
0answers
17 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} \...
0
votes
0answers
29 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 ...
0
votes
0answers
37 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 ...
0
votes
1answer
36 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? ...
0
votes
0answers
17 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 $E_{cell}=Eº_{cell}$....
7
votes
2answers
100 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 ...
2
votes
0answers
21 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 ...
4
votes
2answers
366 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 ...
1
vote
1answer
43 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
votes
2answers
51 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 ...
0
votes
0answers
13 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.
1
vote
1answer
165 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 ...
0
votes
0answers
16 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 ...
1
vote
0answers
122 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? ...
3
votes
0answers
20 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 ...
1
vote
1answer
26 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 ...
2
votes
1answer
51 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 (M/...
4
votes
2answers
80 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 ...
2
votes
0answers
76 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 ...
1
vote
0answers
25 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 ...