Questions tagged [rate-equation]
The rate-equation tag has no usage guidance.
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Pseudo rate equation for catalyzed decompostion of hydrogen peroxide
I am conducting an experiment in which I will be adding a catalyst to a solution of Hydrogen peroxide and will measure its concentration over a range of time by taking samples of the solution every $5$...
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How original is my general matrix formula for rate equations?
I was dissatisfied with the method my teacher taught me to solve rate equations, where you're given experimental values for the concentrations of reactants, and the rate of reaction, which given by
$$...
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1
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Why Michaelis Menten Assumption of equilibrium is necessary to integrate rate of ES production
I read in my textbook that the assumptions of equilibrium and of steady state used by Michaelis and Menten were simplifying assumptions intended to make the following equation one that can be ...
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Does real-world gas phase chemistry use "concentration reaction quotients" (K_c)?
As a theoretical chemist, my entire exposure to reaction quotients and equilibrium constants ($Q$ and $K$) is through thermodynamics ($\Delta G^\ominus = - RT \ln K_{eq}$ and so on).
So as I started ...
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Rate of SN1 reaction in derivative of furan and thiopene
When I was practising questions on the rate of SN1 mechanisms, I stumbled across this:
I could eliminate options B and D because they can stabilize by only cross conjugation (if I am correct) and ...
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What is the physical significance of the frequency factor in the Arrhenius equation?
As the title says, I am wondering what the physical significance of the frequency/pre-exponential factor in the Arrhenius equation. My idea of it is that:
If the units of $E_a$ are energy per molecule,...
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Which reaction to consider for overall rate
So I have a multistep reaction
\begin{align}
\ce{4 NH3 + 5 O2 &-> 4 NO + 6 H2O}\\
\ce{2 NO + O2 &-> 2 NO2}\\
\ce{3 NO2 + H2O &-> 2 HNO3 + NO}
\end{align}
If I know the initial ...
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What equation can be used to determine the mass of water evaporation over time, when cooking?
When baking, cooking or writing recipes, it would be useful to have a ballpark estimate of evaporation rates. This question asks about water, although the answer would ideally include an ...
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2
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What are the differences between the different Rate Equations?
I currently am about to finish general chem 2 so my knowledge is still basic.
There are different kinetics and rate equations and im not quite sure I know the differences.
Breaking rate of a reactant:...
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38
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Rate of reaction and rate constant confusion
If we had the reaction,
$A + B$ $\rightarrow$ $C$, and $A$ was second order, and $B$ was first order, we would say that $rate = k[A]^2[B]$, but this has confused me. When we say $rate$, do we mean the ...
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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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Estimate scaled up rate of gas phase reaction
I have measured the conversion rate of a particulate-catalyzed gas phase reaction in a reactor. That is, I have a graph of how fast $\pu{1 mol}$ of catalyst converts $\pu{1 mol}$ of reactant into $\pu{...
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Calculating rate constant for reaction between potassium permanganate and oxalic acid
I'm writing a lab report investigating the effects of temperature on the rate constant in the reaction between potassium permanganate and oxalic acid. For my practical I've measured the time of colour ...
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Reaction rate derivation: amount of substance vs concentration [closed]
Let's say you have the reaction
$$A + B \; \rightarrow \; C.$$
I would like to understand why $\frac{\mathrm{d}[C]}{\mathrm{d}t}$ is proportional to $[A][B]$. I can see why
$$\frac{\mathrm{d}n_C}{\...
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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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Concentration of products in tank reactor
I want to calculate the concentrations of all components in the outlet stream of the reaction: C$_2$H$_6$ -> C$_2$H$_4$ + H$_2$ (A -> B + C)
I have a tank reactor (isothermic and isobar): V= $...
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Reversible monomolecular reaction with two reverse rates
I think this is a simple problem but my kinetics are terrible and I was hoping for some assistance following up on the work of a previous student. I'm open to any form of assistance and I hope this ...
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1
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Dependence of rate on the nature of reactants and other factors
Consider a reaction
$$\ce{aA + bB -> cC + dD}$$ whose reactants are given by A and B and the products are C and D.
The rate of this reaction is given by $$\frac{dx}{dt} = -\frac{d[\ce{A}]}{adt}= -\...
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How do we know that rates depend on the product and not the sum of reactant concentrations [closed]
I've been struggling to understand the mathematics behind the calculation in enzyme kinetics within systems biology at an intuitive level.
Every research article and textbook says it is based on the ...
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223
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Differential equation in consecutive reactions
I'm blocked in a step of getting to the equation $(7)$, more precisely in the step between $(5)$ and $(6)$. I show my way to solve it down, but I don't get the same as $(6)$, so I wanted to know if I ...
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PFR reactor: -1/r vs conversion plot
A generic reagent A is considered. The behavior equations of a CSTR reactor is the following:
$$
\tau = c_\mathrm{A,0} \intop_0^{X_\mathrm{A,final}}
\dfrac{1}{-r_\mathrm{A}} dX_\mathrm{A}
$$
where $\...
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Serial reactions or consecutive reactions: rate vs time
Serial reactions, or consecutive reactions, are two or more reactions in which the product of the first reaction becomes the reactant in the next. The simplest case of a serial reaction involves a ...
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How does the stoichiometric coefficient affect the time until a given percentage of the reactant is consumed (if at all)?
Problem from Serway's College Physics test bank:
The reaction $2NO_2\rightarrow2NO+O_2$ obeys the rate law:
$\large \frac{\Delta[O_2]}{\Delta t} = (1.40\times10^{-2})[NO_2]^2 \space at \space 500^\...
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How to rewrite kinetic mass balance to get to proper SI units?
Suppose from kinetic mass balance I get the following differential equation of the molarity substances $A$,$B$, and $C$ in a reactor, with molar in- or outflow rate $\phi$, and rate constant $k$:
$$
\...
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What are the reaction rate constants, or coefficients, of coal combustion at high temperature?
Say I have coal that I will combust with $\ce{O2}$ at a high temperature of $\pu{1600-1800 K}$, what are the reaction rate constants, or coefficients, of the main reactions?
I have searched around ...
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In regards to the Gibbs free energy equation, it seems that the two terms oppose one another, Enthalpy and -TS. Can you explain this?
So for example, if H is endothermic, then the enthalpy term is positive, meaning energy is absorbed by system overall, meaning net bonds broken, meaning the equation leans towards nonspontaneity. If ...
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Rate order when the slow step only contains intermediates?
I feel a bit sheepish asking this, but I was told that the stoichiometry of the slow step of a mechanism indicates the order of a reaction with respect to a reactant. However, in the slow step of this ...
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Modelling barrier-less reactions
I am currently exploring a few dissociative reactions whose PES is barrierless (no first order saddle point). I have found a few approaches in literature like flexible nudged elastic band theory, ...
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Calculate the concentration of the reactant from the absorbance of the product without molar absorptivity
Given the reaction $\ce{A->B}$, where the absorbance of the product $\ce{B}$ has been measured (see the table below), and the initial concentration of $\ce{A}$ is $\pu{10^{-4} M},$ calculate the ...
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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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pH for optimal kinetic for enzyme reaction
If I am given the following enzyme reaction:
where K$_{EH,1}$=K$_1$ = $10^{-4}$ and K$_{EH,2}$=K$_2$ = $10^{-8.2}$. Iwant to calculate at which pH I have the optimal kinetics by calculating $\frac{v'...
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Calculating ionic strength at different concentrations
Zn$^{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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Tmax of parallel reactions/Steady state reactions
Below are four reactions, to this experiment inhibitor is added so that k$_3$ = $0$ (but the other reactions are unaffected) calculate [D] when the reaction is over. The initial concentration of A is $...
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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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1
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How to calculate rate of carbon dioxide from rate equation? [closed]
The concentration of carbon dioxide that changes with time:
$$\ce{CO2(g) + H2O(l) <=>[$k_\mathrm{fwd}$][$k_\mathrm{rev}$] HCO3-(aq) + H+(aq)}$$
How to calculate the integral for the following ...
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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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1
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Rate equation for the decomposition of hydrogen peroxide with iron(III) chloride as catalyst [duplicate]
I am trying to determine the activation energy of the decomposition of hydrogen peroxide with iron(III) chloride added as a catalyst. To do that, I need to find the rate constant, but I am not sure ...
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Does 'k' in the rate law change with a change in volume
I'm a high school AP Chem student and we recently learned about the rate law and the Arrhenius equation. In school, we learned that rate constant 'k' is only changed with temperature or catalyst. ...
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Rate of Reaction - Potassium Permanganate and Hydrogen Peroxide
I'm interested in an aerospace project that requires I know the reaction rate ($[\pu{M/s}]$) of,
$$\ce{2 KMnO4 (aq) + 3 H2O2 (aq) -> 3 O2 (g) + 2 MnO2 (s) + 2 KOH (aq) + 2H2O (l)}.$$
I'm just ...
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Are there any genuine, elementary ternary reactions?
Macroscopically, reaction rates can be of varied order. But mechanistically, most reactions are first-order or second-order/binary (e.g. SN2, many catalyst surface reactions, dimers). Most processes ...
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Writing rate of disappearance and rate of appearance using rate law [closed]
I have studied that rate of disappearance and rate of appearance is the change in concentration of reactants and products (respectively) with respect to time. Thus,
$$\text{ROD} = -\frac{\Delta c_R}{\...
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Assuming 2O3 (g) → 3O2 (g), how much oxygen will be formed within 5.50 s for a reaction rate of 0.250 M/s?
Context: The rate of appearance of $\ce{O2}$ in the reaction: $\ce{2O3 (g) -> 3O2 (g)}$ is $\pu{0.250 M/s}$. So, over the first $\pu{5.50 s}$, will it form $\pu{1.38 M}$, or $\pu{4.13 M}$ of oxygen ...
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What is the rate law of a reaction: 2A + 3B → products? [closed]
Update: I found out that the coefficients of the chemical reaction are not the exponents in the rate law. It is actually the order of the species during the reaction.
It is known that in the reaction, ...
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1
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Problem understanding the rate of reaction of reversible reactions
Case 1:
$$\ce{CH_3COOH + NaOH<=>CH_3COONa + H_2O}$$
At equilibrium, there remain extremely small concentrations of the reactants (acetic acid and sodium hydroxide), and comparatively large ...
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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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Can an elementary reaction have zero order?
I am very confused right now about my approach to this question could somebody help me out with this. I reasoned my answer as given below
Let's assume if a complex reaction is of zero order. It ...
user117301
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366
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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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Determining ion charge using rate constants and ionic strength
I am given the following data:
The rate constant $k$ at $\pu{25 ^\circ C}$ in a reaction of persulfate ions and iodide ions in a water solution is assumed to vary with the total ionic strength of the ...
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