Questions tagged [kinetics]
The study of rates and steps in mechanisms of chemical processes.
807
questions
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6 views
Is the molecularity of the slowest step equal to the order of the slowest step of the same reaction? [closed]
My book says "YES" , to the above question. However, i say "NO" .
Please tell me whether my book is right or me.
-1
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0answers
43 views
How can the rate of reaction between thiosulfate ion and acid be calculated as v = 1 M/Δt? [closed]
The experiment is done in the following way:
Sodium thiosulfate is added in a beaker (the concentration is noted).
Acid is added (the same amount each time).
Time is taken till the reaction reaches ...
0
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2answers
37 views
Can I determine the rate law order from stoichiometric coefficients?
I've read in two books, and seen in three separate videos courses, that you cannot determine the rate law order from stoichiometric coefficients.
Then, I have seen homework and "practice" problems ...
2
votes
1answer
85 views
How to set up an equation to solve a rate law computationally?
I am confused on how to set up my equations to use in the solver. I have an equation
$$\ce{A + 2B -> C}$$
As a given, it is first order in A and second order in B. What I need to do is to solve for ...
1
vote
0answers
26 views
What is the activation energy of a Daniell cell?
I'm having trouble finding a posted literature value for the activation energy for the Daniell cell redox reaction:
$$\ce{Cu^2+ + Zn -> Cu + Zn^2+}$$
Where might I be able to find this ...
-2
votes
1answer
24 views
What is the molecularity of a reaction if it has a fractional order as per rate equation? [closed]
The rate equation of any reaction is found by using its slowest step.
My book says that molecularity of the slowest step of a reaction is equal to the order of the same reaction.
However, there are ...
2
votes
1answer
44 views
Rate of reaction involving different stoichiometric coefficients
Suppose I have a reaction (Say it is the Haber process):
$$\ce{N2 + 3H2 <=> 2NH3}$$
If we have to calculate the average rate of reaction of the above we follow the reasoning the rate of ...
0
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1answer
26 views
Rate determining step for parallel reaction?
I have always read that the rate determining step is the slowest step in a reaction (source: Wikipedia).
In chemical kinetics, the overall rate of a reaction is often approximately determined by ...
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0answers
18 views
Is rate equation for an overall chemical reaction same as rate equation for the slowest step of the same? [closed]
Is molecularity of the slowest step same as the order of the rate equation?
2
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0answers
21 views
Order of Reaction differs in equation and linearisation
I have given the following equation: $A + 2B \rightarrow C$
$ v = –k\cdot [A]\cdot[B]^2$
gives me the orders 1 for A and 2 for B. That results in a total order of the reaction of 3.
So far so good. ...
2
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2answers
29 views
How does the rate constant change with the change of the temperature?
In class, we discussed the following multiple-choice question.
The rate expression for a reaction is:
$$rate = k[X][Y]$$
Which statement is correct?
A. As the temperature increases, the ...
1
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1answer
53 views
How to derive the steady-state solution for simple two-step reaction with differential equations? [closed]
Consider this simple two step reaction, a variant of a Michaelis-Menten type of problem, where $\ce{A}$ and $\ce{B}$ reversibly bind to make $\ce{AB}$, and $\ce{AB}$ and $\ce{C}$ reversibly bind to ...
3
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2answers
129 views
General justification for steady state approximation
I want to understand the assumptions that have to be fulfilled in order for the steady state approximation to work. I did some research myself and was able to deduce assumptions of the form $k_1\gg ...
-1
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0answers
14 views
Help required with calculation of reaction rate for a chemical reaction
*Note: This is not a homework problem but something related to my research! Thanks
I'm simulating a metal droplet suspended in a reactive medium. The droplet tends to react with the injected gas as ...
1
vote
3answers
45 views
Is the kinetic energy change of a system (q) equal to the enthalpy change of a system (∆H)?
When silver nitrate and hydrochloric acid are put together in a container, they form silver chloride. If you're given information about the reactants (including temperature change, heat capacity, and ...
2
votes
1answer
70 views
Why doesn't nitrogen react with oxygen at room temperature? [closed]
I already know that nitrogen's triple bond requires a lot of energy to be broken, so the activation energy is very high, but the book also lists the endothermic energy change as a reason.
Does the ...
0
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1answer
74 views
How to precipitate Chloroplatinic acid? [closed]
For the precipitation reaction, I have to react $\ce{H2PtCl6}$ with $\ce{(NH4)2CO3}$ while maintaining the $\ce{pH}$ in the range of 7-8 at 60 °C. But the problem is Chloroplatinic acid is not ...
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0answers
44 views
For a 1st order reaction, how do you derive the integrated rate law for a product versus time?
For a chemical reaction in which some stoichiometric quantity of arbitrary chemical $A$ decomposes into products $B$ and $C$,
$$a \ce{A} \ce{->} b \ce{B} + c \ce{C}$$
or more simply:
$$a\ce{A} \...
3
votes
2answers
54 views
Deriving rate law from a reaction mechanism for a chain reaction using steady-state approximation
I am trying to derive the overall rate equation for the photocatalysed halogenation (chlorination) of an alkane that proceed via this 4 step chain reaction:
$\ce{Cl2->2Cl^. \quad(1) initiation}$ ...
0
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2answers
66 views
Unusual Result in Kinetics Lab
The question: In the lab described below, why did the decolorization reaction described, which should be first order in each of the two reactants, go most slowly when the reactants were most ...
3
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3answers
480 views
Can I express the rate of a reaction as percent per second (%/s)?
Rate is calculated as change in concentration over change in time, so usually $\pu{M/s}$ $(\pu{mol L-1 s-1}).$
Say, I'm calculating it for $20\%$ solution of ammonium hydroxide, so my final rate is ...
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0answers
75 views
Controlling rate of endothermic reaction
In an experiment, I have two endothermic reactions taking place simultaneously:
$$
\begin{align}
\ce{A + B &-> C + D}\tag{1}\\
\ce{E + G &-> Z + F}\tag{2}
\end{align}
$$
$\ce{C}$ and $\...
1
vote
1answer
17 views
R and T conformations in relation to Activators and Inhibitors; Km of reaction in relation to uncompetitive and non-competitive inhibitor
Do
-Activators
-Competitive Inhibitors
-Non-Competitive Inhibitors
-Uncompetitive Inhibitors
all change the conformation of the targeted enzyme from T to R (activator), and from R to T (the rest) ...
1
vote
2answers
48 views
Does the concentration of water accounts for determining the rate of a reaction?
I found this problem in my book and I'm not sure how to assess this question.
It is as follows:
Regarding the relationship between the rates of the chemical species
in the following reaction. ...
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votes
2answers
82 views
What is the rate equation of decomposition of H2O2 with catalysts?
What is the rate equation of this reaction with the presence of catalysts $\ce{MnO2}$, $\ce{PbO2}$ and $\ce{Fe2O3}$? (asking for each of them, separately, not altogether)
$$\ce{2H2O2 -> 2H2O + O2}$...
8
votes
2answers
985 views
If a reactant appears on both sides of an elementary equation, can it be cancelled?
Me and a friend were debating the following. For the elementary reaction
$$\ce{A + B -> A + C}$$
my friend says that it is unimolecular because $\ce{A}$ does not "participate" in the reaction. So,...
0
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0answers
21 views
Can the relative reactivities of different compounds that undergo the same reaction be compared if the compounds follow different overall kinetics?
I have read that if some different compounds undergo the same reaction and under the same conditions, but follow different overall kinetic orders, then their rate constants or relative reactivities ...
3
votes
2answers
58 views
Preparation of Barium Hexaaluminate using co-precipitation reaction mechanism
I am preparing Barium Hexaaluminate (BHA) using $\ce{Ba(NO3)2, Al(NO3)3}$, and $\ce{(NH4)2CO3}$. For $\pu{1 mol}$ of each $\ce{Ba(NO3)2}$ and $\ce{Al(NO3)4}$, I am using $\pu{1.5 mol}$ of $\ce{(NH4)...
1
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1answer
47 views
Writing a system of differential equations with the given arbitrary reactions
We have the following elementary reactions:
\begin{align}
&\overset{k_1}{\longrightarrow}A\overset{k_2}{\longrightarrow}{B+C}\\
&C \overset{k_4}{\longrightarrow} 2D \overset{k_5}{\...
3
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1answer
36 views
A “function of proportionality” in a rate law [closed]
I am currently studying rate laws and the determination of the order of a reaction. So first-order reactions remind me of linear functions $f(x)=kx$ while second-order reactions remind me of quadratic ...
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0answers
26 views
How does the temperature affect the frequency factor?
I am a high school student and have been trying to learn how the temperature affects the frequency factor. I did not even understand the equation below, which is from this site. Can anyone please ...
0
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1answer
62 views
Are the reaction rates of these equations equal? [closed]
$$\ce{CH3CH2CH2Br + OH- -> CH3CH2CH2OH + Br-}$$
$$\mathrm{rate} = k[\ce{CH3CH2CH2Br}][\ce{OH-}]$$
If I change the $\ce{Br}$ with any element from halogens (without changing concentration, volume, ...
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0answers
31 views
Using calculus to find the rate of a bivariate reaction
Recently, I've been learning about rates and have found the concept fairly easy to understand in the case of a reaction with a single reactant, which is essentially solving $$f'(t) = kf(t)^n$$ where $...
3
votes
1answer
57 views
The reaction rate when the rate-determining step has a back reaction
For some reason, I am reviewing general chemistry and I find that the elementary reaction for the rate-determining step (RDS) is assumed to be irreversible, that is, single arrow, in all questions ...
0
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1answer
33 views
Sum of a rate constant gives the total decay rate
I want to ask a question about the sum of a rate constant to yield the total decay rate.
From previous studies, the rate of a reaction can be expressed evidently as
$$\ce{v_{rate} = k[A]}$$
where ...
1
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0answers
36 views
Rate determining step in oxidation of alcohols using chromium-related compounds
I wanted to ask a question about the kinetics of an oxidation reaction using chromium reagents.
I was given a lecture today on the mechanism of alcohol oxidations using Chromate (VI) reagents:
My ...
0
votes
1answer
53 views
How much oxygen is formed in this first order reaction? [closed]
We have a reaction
$$\ce{2N2O5 -> 4NO2 + O2},$$
which has a rate constant $k=6,2\cdot10^{-4}/\mathrm{min}$ at temperature $T=318.15\ \mathrm{K}$. How much oxygen is formed in litres when $1.00\ \...
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0answers
54 views
Literature value for the activation energy of the reaction between hydrochloric acid and sodium bicarbonate
Does anybody have the literature value for the activation energy of the reaction between hydrochloric acid and sodium bicarbonate? If yes, could you please cite the source for it and the value?
I ...
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0answers
43 views
Why do the NMR peaks shift when H+ concentration and temperature are varied on the reversible hydrolysis of pyruvic acid to 2,2-dihydroxypropionate? [closed]
We performed two experiments. Each of the peaks are referring to the methyl peaks in both reactant and product of the hydrolysis reaction.
We varied $\ce{H+}$ concentration of the reaction and the ...
1
vote
0answers
134 views
Order of reaction in adsorption process
(1) $\ce{PH3(g) <=>[W]PH3(adsorption)->[W]P(s) + 3/2 H2(g)}$
The decomposition of phosphine on tungsten surface at low pressure is a pseudo first order reaction. This is because the rate of ...
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0answers
26 views
Convert to NASA polynomial format for chemical kinetic calculations
I have calculated thermodynamic properties of a metal oxide through DFT calculations, I want to convert it to NASA polynomial format and use those thermodynamic properties along with rate constants ...
0
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1answer
47 views
Order of reaction for hydrogen ions being ignored
I have been reading through a case study about calculating the order of reaction for the following reaction:
$$\ce{H2O2 + 3 I- + 2 H+ -> I3- + 2 H2O}$$
The paper uses an iodine clock reaction ...
0
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0answers
32 views
Why do statistical effects impact stepwise stability constants?
I have a question regarding the stepwise stability constants of metal complex formation/substitution.
My lecture notes say that if we have a metal complex, say $\ce{[MX_{6}]}$, and a substitution ...
0
votes
1answer
57 views
Finding change in activation energy from change in rate constant in catalysis
I need to find by how much the activation energy decreases when the rate constant increases by a '$x$' factor when a catalyst is used in the reaction.
I'm just super confused about how to solve this....
0
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0answers
399 views
Which is faster- SN1 or SN2?
We were studying about nucleophilic substitution reactions. My professor said that in general SN1 reactions are faster than SN2 reactions. I am unable to understand that how can we generalise the rate ...
0
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0answers
33 views
Can I use the quasi-equilibrium approximation when drug and ligand distribution volumes are different?
A drug $D$ binds a ligand $L$ to form a complex $C$ according to the law of mass action. Furthermore, mass balance should be achieved. Can I still assume quasi-equilibrium when the distribution ...
0
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0answers
78 views
Chemical Kinetics regarding Iodination of Cyclohexanone
We did an experiment to determine the overall order of iodination of cyclohexanone.
Rate of a certain chemical reaction = $\ce{k[A]^p[B]^q[C]^r}$
so the overall order = p+q+r
We're referring to a ...
5
votes
1answer
409 views
Chemical kinetics
Consider a reversible reaction $\ce{A}$ converts to $\ce{B}$ and $\ce{B}$ converts to $\ce{A}$ with forward and backward rate constants $k_\mathrm{fwd} = k_\mathrm{rev }= \pu{1 s-1}.$ Suppose we start ...
2
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0answers
50 views
Explosive reaction based on reaction rate
Question
We have the following chemical reactions:
$$
\begin{align}
\ce{A + B^* &-> C + D^*}\tag{1}\\
\ce{D^* &-> B^* + B^*}\tag{2}\\
\ce{B^* &-> B}\tag{3}
\end{align}
$$
...
-1
votes
1answer
42 views
Rate Expression with two products
Consider the two following cases
Case 1: Two Same Products
Given the following chemical reaction,
$$A + B \rightarrow C + C$$
where C are radicals, therefore I am not writing $2C$ on the right ...
