Questions tagged [reaction-order]
The reaction-order tag has no usage guidance.
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Why is concentration never zero for zero order reactions? [closed]
By formula of zero order reaction:-
$$C_t=C_o-kt$$
The concentration should be zero at $t=C_0/k$. But in some books and websites I saw that graph between concentration and time don't touch the X-axis. ...
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Why decomposition of gas on metal surface at high pressure considered 0 order
While reading my textbook it says that when ammonia decompose on a platinum surface at high pressure, the reaction is 0 order because at high pressure the metal surface get saturated with ammonia ...
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How to interpret gas chromatography results?
I am having trouble interpreting gas chromatography (GC) results for the production of ethyl acetate from acetic acid and ethanol. I am trying to find the reaction order from these results, as well as ...
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How to write a rate expression when one reactant is not soluble?
For a chemistry experiment, I would like to determine the rate expression for the reaction between zinc and hydrochloric acid. Given that zinc is not soluble in the water, would I use a "false&...
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Solving for Partial Pressure given first-order decomposition
From my GenChem practice exam:
Consider the following reaction:
$\ce{C4H8 (g) → 2C2H4 (g)}$
The first-order decomposition of cyclobutane to two molecules of
ethene has a rate constant of $\ce{9.20\...
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Order of reaction with and without the presence of catalyst
When ethene reacts with hydrogen to give ethane in the presence of Ni, the order of the reaction is 2, if I am not wrong, please correct me if I am. But if we remove the catalyst, and simply allow ...
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Can the overall order of a reaction ever be strictly less than $1$?
In A-level chemistry we are taught that:
To every reaction: $$\sum_{i=1}^n c_iA_i\to\sum_{j=1}^m d_jB_j$$There is a rate equation: $$r=\kappa[A_1]^{\alpha_1}[A_2]^{\alpha_2}\cdots[A_n]^{\alpha_n}$$...
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Temperature dependence of order of reaction
In my textbook, it is given that the order of a reaction can change with temperature and pressure, but examples are not given. One possible explanation for this is that the rates of complex reactions ...
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Why can't the half-life be determined in a reaction with more than one reactant?
We have a second order irreversible reaction with 2 reactants (A and B, order 1 for both) so that the initial concentrations are different. I've read that the half-life doesn't make sense in this ...
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Negative or fractional order of reaction
Let $\ce{A}$ be the reactant and $\ce{P}$ the product at the imaginary elementary reaction $\ce{A->P}$.
Could it possibly have a net total order of $-1?$
$$-\frac{\mathrm d[\ce{A}]}{\mathrm dt} = k[...
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How to rationalize independence of half-life time from the initial concentration for the first order reaction?
Using the rate expression for the first order kinetics and expressing the half-life time, it can be proven the half-life time $t_\frac 1 2$ of the first order reaction is independent of its initial ...
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Does E1 mechanism always imply first order reaction?
Oxford University Press, Okuyama & Maskill: Organic Chemistry — Chapter 13: Multiple Choice Questions, Question 1:
Which of the following statements regarding the E1 mechanism is wrong?
a) ...
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Confusion regarding order of reaction
The following points are given in my textbook about order and molecularity:-
(i) Order of a reaction is an experimental quantity. It can be zero and even a fraction but molecularity cannot be zero or ...
user121185
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Calculate rate constant of second order reaction and pseudo first order reaction
The reaction A + B -> Prod follows the second order kinetics. In an experiment, you initially have ten times as much B
as A. The concentration of A varies with time according to the following data:
...
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Calculating ionic strength at different concentrations
Zn$^{2+}$ reacts with a molecule, B, in a solution at several different concentrations of NaCl.
Determine the charge of the biomolecule and k$_0$ (second order) (assume that Zn$^{2+}$ does not ...
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Why is it that first order reactions never end? [duplicate]
I'm studying chemical kinetics in high school. We are studying Integrated Rate Equation of first order reactions - their derivations and graphs. Our teacher showed us a graph of:
Concentration of ...
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Determine reaction order of Cyclopentadiene
Reaction: $\ce{2 C5H6 -> C10H12}$
For this reaction it is stated that $\pu{0.609 M}$ cyclopentadiene was formed in an ethanol solution. When the solution was heated $(\pu{40 ^\circ C})$ and ...
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Can two 1st order reactants in an overall 2nd order reaction have different rates?
I've recently done a saponification reaction of ethyl acetate with sodium hydroxide and used the initial rates method to find the order of reaction. (I change the concentration of one reactant and ...
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(Beginner Question) Reaction Word Problems [closed]
I am having trouble understanding how to create equations which can then be balanced. For example, if I am told that a freshly scraped piece of aluminum reacts with oxygen from the air to form a ...
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What are some three+ stage cyclical reactions that only go one direction?
I was imagining the origins of life and supposed that "humans are just a bunch of cyclical chemical reactions in a coat." Which made me wonder, what sort of cyclical chemical reactions ...
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Finding the reaction order from a given plot of chemical kinetics
What will be the order of the reaction for a chemical change having $\log t_{1/2}$ VS $\log a$ Where $a=$ Initial concentration of reactant and $t_{1/2} =$ Half Life?
0 order
1st order
2nd order
None ...
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The Mechanism of Termolecular Reactions
How does a termolecular elementary reaction happen under the law of mass action? My physical chemistry textbook only says details about bimolecular and unimolecular reactions with collision theory. I ...
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Are there any pathways that can change a solution to all colors of the rainbow?
The challenge's like this. Suppose you have a beaker containing a liquid of transparent or any color. You add some drops of another liquid and the beaker turns into, say, red after some swishing. You ...
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Calculate concentration of product after time passed
If I have two parallel reactions:
A --> P$1$ (k$_1$ = $0.00010$ s$^{-1}$)
A --> P$2$ (k$_2$ = $0.00050$ s$^{-1}$)
and know that the initial concentration of A is $0.0417$ M. How can I ...
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Determining reaction order from absorbance
A reaction is initiated in a solution which contained a dissolved component. The transmittance was measured at $\pu{240 nm}$ in a $\pu{2.54 cm}$ long cell. At $t = 0$ the transmittance was $1$. $\...
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Plotting second order reaction with different reactants
In a laser flash photolysis experiment, $\ce{C6H5NH2}$ $(C_0 = \pu{60 \mu M})$ is oxidize to its corresponding radical cations. There are three possible reaction pathways for the formation of the ...
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How do the terms in a rate law relate to effectiveness and number of collisions of reactants?
In chemical kinetics, we use rate law to find the instantaneous rate of reaction.
Let us consider a simple reaction
$$\ce{aA + bB -> products}$$
where the rate law is
$$\mathrm{rate} = k[\ce{A}]^a[\...
user112830
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How to graph a second order reaction with two different reactants
In a laser flash photolysis experiment, $\ce{C6H5NH2}$ $(C_0 = \pu{60 \mu M})$ is oxidized to the corresponding radical cation. The disappearance of radical cation is monitored spectrophotometrically ...
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First or second order reaction
I have that $100$ mM of K$_3$Fe(CN)$_6$ is dissolved in equimolar of the organic ion (which I assume is HCN). In the solution Fe(CN)$_6$$^{3-}$ reacts to form Fe(CN)$_6$$^{4-}$.
The formation of Fe(CN)...
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Is the rate of a zero order reaction always independent of the concentration of its reactants?
Consider the following reaction :
$\ce{A + B}$ $\rightarrow$ $\ce{Products}$
where order of the reaction w.r.t. $\ce{A}$ is $-1$ and order of the reaction w.r.t. $\ce{B}$ is $+1$. So, overall order of ...
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Determine reaction order and reaction rate
In a solution of $\ce{Fe^3+}$ the concentration was measured to be:
$$\begin{array}{c|c}
t/\pu{min} & \ce{[Fe^3+]}/\pu{\mu M} \\ \hline
10\ & 238\\
20 & 227\\
40\ & 206\\
60\ & ...
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Are the orders of reactants with respect to a reaction different for different starting concentrations?
If the reaction is repeated with $\pu{2 M}$ ethyl iodide the pyridine concentration decreases as shown below. Give the rate law of the reaction in terms of pyridine and ethyl iodide. Explain your ...
user85551
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Formula for rate constant for the first order reaction
My lecturer mentioned that the formula for the rate constant $k$ for the first order reaction is
$$k = \frac{2.0303}{t_{1/2}}\,\log\frac{[\ce{A}]_0}{[\ce{A}]_{t_{1/2}} - [\ce{A}]_0},\tag{1}$$
where $...
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In reaction equations, why are j and k sometimes capitalized to J and K?
From 'Leighton relationship' on Wikipedia:
through the following mechanism:[2]
($J_1$) $$\ce{NO2 + h\nu (\lambda < 420 nm) → NO + O (^3P)}$$
($k_2$) $$\ce{O (^3P) + O2 + M → O3 + M}$$
($k_3$) $$\ce{...
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Arrange in the order of their reactivity of SN2 reaction
Here in case of (1) it is more favorable towards SN1 reaction as it will create benzyl carbocation which is very stable.
(2) Here it is more favorable towards SN1 as it is first of all allyl ...
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Relationship between molecularity and the reaction order
Should the molecularity be equal or less than the reaction order?
Consider the reaction:
$$\ce{H2(g) + I2(g) → 2 HI(g)}$$
If we consider the mechanism of this multi-step reaction, the molecularity is ...
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Parallel reactions for one product
For me it is clear how I could solved the kinetic of a parallel reaction like this
But, how can I solve if this would be the case:
Thanks in advance!
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Is this statement valid for reactions of all orders? [duplicate]
My textbook (not an international standard) states that for the first order reactions only
The quantity of reactant remaining after $n$ half lives is
$$A_n = \frac{A_0}{2^n},$$
where $A_0$ is the ...
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Inconsistency in Elementary Bi-Molecular Reaction Rate Expressions
Assume the following bi-molecular reaction is elementary as written with rate constant $k_\mathrm{f}$:
$$\ce{A + A -> P}$$
This review, suggests to express the rate in terms of the production of ...
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Catalysts and activation energy
Do catalysts increase rate of reaction only by decreasing activation energy? Or can they affect the Arrhenius factor or reaction orders? Like if one catalyst is more effective at increasing rate of ...
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Balancing reactions algebraic method limitations [duplicate]
How do I balance this reaction using the algebraic method?
Seems that the equation can't be solved.
How do I balance such reaction and does the algebraic method has limitations and wont work for ...
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Second order reaction with different reactants
In a laser photolysis reaction $\ce{C6H5NH2}$ $(C_0 = \pu{60 µM})$ is oxidized to its radical cation. The disappearance of the cation can follow three pathways: (1) Dimerzing of the cation, (2) ...
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Can iodine replace other halogen as well?
While reading about halogen family I encountered the reaction:
$$\ce{NaClO3 + I2 -> NaIO3 + Cl2}$$
I know that that the oxidizing tendency of halogens decreases down the group, so I think that the ...
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Find order of reaction 2A → B + C
Derive the integrated rate expression for a reaction of type:
$$\ce{2A -> B + C}$$
I first need to determine the order of the reaction in order to find integrated rate law of that particular order....
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How is the Rate law of a reaction measured?
What is the Rate law of the reaction below?
$$\ce{4 HBr + O2 -> 2 H2O + 2 Br2}$$
How do we approach finding the rate law of a reaction? Can this be found out only through experiments?
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