Questions tagged [rate-equation]

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Derivation of form of rate laws [closed]

for a given reaction $A \rightarrow B+C$, I read in my book that the rate law has to be of the form $$ \frac{d[A]}{dt} = - k[A]^m $$ Can someone tell me (or point to some sources) on how we know the ...
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Is it possible to calculate the theoretical rate of reaction?

I am conducting an experiment where I will be changing concentration (0.2 mol/dm3, 0.4 mol/dm3, 0.6 mol/dm3, 0.8 mol/dm3, 1.0 mol/dm3) and seeing how that affects the rate of reaction for a reaction ...
Science Central's user avatar
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1 answer
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HCN reactor design

For my diploma work, I should design a hydrogen cyanide (HCN) producing reactor. I found that for the BMA process, overall $$\ce{CH4 + NH3 -> HCN + 3 H2 \quad{} \Delta{}H_r = \pu{251 kJ / mol} }$$ ...
Laman Alipashayeva's user avatar
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A first order gaseous reaction - getting the rate law

There is a specific example cited in our NCERT Class 12 textbook, to find out the rate law equation for a general gaseous reaction, $$\ce{A->B + C}$$ It describes the entire procedure as shown: ...
Chem-geek0's user avatar
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Is my derivation for the reaction orders of a single-step reaction valid?

Recently in my chemistry class I learned about reaction orders. For some reaction $\ce{r_1A1}+\ce{r_2A2}+\dots+\ce{r_nA_n}\rightarrow\ce{B}$, $m_1,\dots{,m_n}$ are the orders of that reaction. The ...
Eyeballer's user avatar
2 votes
1 answer
101 views

Calculate IC50 from fluorescence kinetic

I have an assay in which a fluorescence signal is generated when the enzyme reaction progresses. The fluorescence signal increases until a maximum is reached. Than it keeps constant. The first 1 h ...
raptorlane's user avatar
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Why isn't the unit of rate constant for any reaction always per second?

It is formally agreed upon that $K_{eq}=\prod_{j}a_j^{\nu_j}$ where $\nu_j$ is stoichiometric coefficient of species $j$ (negative for reactants and positive for products). This equation results in ...
megamonster68's user avatar
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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 $$...
Jamie Cline's user avatar
2 votes
1 answer
78 views

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 ...
Zak's user avatar
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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 ...
Shern Ren Tee's user avatar
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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,...
PhysPhil's user avatar
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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 ...
A Random Squid's user avatar
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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 ...
JKVeganAbroad's user avatar
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2 answers
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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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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&...
Guest's user avatar
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2 answers
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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\...
Mailbox's user avatar
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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{...
jackisquizzical's user avatar
1 vote
1 answer
531 views

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 ...
aayush's user avatar
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2 answers
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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}{\...
Silenus's user avatar
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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= $...
katara 's user avatar
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2 votes
1 answer
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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 ...
hotmaildotcom1's user avatar
1 vote
1 answer
52 views

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}= -\...
Shashaank's user avatar
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1 answer
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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 ...
Dendrobium's user avatar
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1 answer
302 views

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 ...
Jorge Bonifaz's user avatar
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1 answer
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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 $\...
user3713179's user avatar
1 vote
1 answer
243 views

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 ...
user3713179's user avatar
-1 votes
1 answer
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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^\...
Saif Taher's user avatar
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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 $k$: $$ \...
user313866's user avatar
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0 answers
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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 ...
user313866's user avatar
-2 votes
3 answers
106 views

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 ...
Steven's user avatar
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2 votes
1 answer
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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 ...
yolo's user avatar
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3 votes
1 answer
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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, ...
Arun's user avatar
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3 votes
1 answer
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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 ...
katara 's user avatar
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0 votes
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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: ...
katara 's user avatar
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1 vote
1 answer
237 views

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'...
katara 's user avatar
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0 answers
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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 ...
katara 's user avatar
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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 $...
katara 's user avatar
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1 answer
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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 ...
sysgrammer's user avatar
1 vote
1 answer
439 views

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 ...
17051411's user avatar
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0 answers
33 views

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 ...
Alan Liu's user avatar
-1 votes
1 answer
225 views

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 ...
Melisa Civelekoglu's user avatar
3 votes
2 answers
357 views

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. ...
Dylan Ong's user avatar
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1 answer
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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 ...
Matt Tucker's user avatar
10 votes
1 answer
288 views

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 ...
alexchandel's user avatar
-1 votes
1 answer
1k views

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}{\...
Spencer's user avatar
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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 ...
Aidre Cabrera's user avatar
-1 votes
2 answers
2k views

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, ...
Aidre Cabrera's user avatar