The study of rates and steps (mechanisms) of chemical processes.

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Calculating K Value of a Clock Reaction

Uncertainty Not Included Some Units Not Included R2 value calculated from Header (Concentration, 1 over Concentration and LN Concentration) vs Time Column of ...
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1answer
62 views

Is the Arrhenius Equation only valid for reactants in the gas state?

I couldn't find a source that explicitly say this, but given the gas constant R is used, is the Arrhenius equation only valid when all reactants are gases? Do they have to be ideal gases? If the ...
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2answers
176 views

What is the order of the reaction with respect to NO?

According to a question on my book, The following reaction mechanism has been proposed for the reaction of $\ce{NO}$ with $\ce{Br2}$ to form $\ce{NOBr}$ $$\ce{NO(g) + Br2(g)<=>NOBr2(g)}$$ ...
3
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1answer
48 views

Initial rate of reaction from the graph?

#13 , I tried finding the slope between two points but I keep getting wrong values, how do you find the initial rate? So I started by trying to find a slope of two points. (0,0.4) and (10,0.2) after ...
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1answer
52 views

Reaction kinetics, relating half life to reaction rate

How do I relate the half life to the overall rate of reaction? I argued that from the data, doubling the partial pressure of either reactant, keeping the other constant, will half the half life. ...
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35 views

Kinetics Rates-Orders

Given the initial rate data for the reaction A + B → C, determine the rate equation for the reaction. ...
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33 views

Conditions affecting pseudo rate orders

For the reaction: $$\ce{F + Br_2 -> FBr + Br}$$ The gas concentrations as a function of time are given by: $$kt=\ce{\frac{1}{[Br2]_0-[F]_0}}\ce{\ln(\frac{[Br2][F]_0}{[F][Br_2]_0})}$$ Given that ...
3
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1answer
32 views

Equilibrium constant in terms of mole fractions

$$\ce{CO + H2O <=> CO2 + H2}$$ A stoichiometric mixture of $\ce{CO(g)}$ and $\ce{H2O(g)}$ is allowed to reach equilibrium. $x$ is the mole fraction of $\ce{H2(g)}$ present. I am meant to ...
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1answer
34 views

Computing the concentration of a reactant given formation of products

At high temperatures nitrogen dioxide decomposes into nitrogen oxide and oxygen gas according to $$\ce{2 NO_2 -> 2 NO + O_2}$$ I have a question now. Let's say at a certain temperature I'm given ...
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18 views

Computing initial reaction speed given reaction constant

Problem: $\ce{N2O}$ falls apart in oxygen gas and nitrogen gas according to a first order reaction rate. If you know that the rate constant is $0.38\ \mathrm{s^{-1}}$ at $760\ \mathrm{^\circ C}$, ...
3
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1answer
84 views

Law of mass action

If you have the forward reaction $$\ce{2X -> P}$$ at rate $K$, would you have $$\frac{\mathrm{d}[\ce{X}]}{\mathrm{d}t} = -2K[\ce{X}]^2,\ \frac{\mathrm{d}[\ce{P}]}{\mathrm{d}t}=K[\ce{X}]^2,$$ or ...
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1answer
67 views

Unit consistency in rate equations

I suppose that my problem is not one of great profundity, but it is an annoying one. The problem is related to the measurement units involved in rate equations of different order. Not being a chemist ...
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1answer
64 views

Predicting incomplete combustion?

I understand the concept of incomplete combustion and that it occurs when oxygen is not a large enough supply to allow for complete combustion. My question is: how can we model combustion properly in ...
0
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2answers
58 views

Why is it the case that KE = 0.5mv^2

To the best of my knowledge, energy equals work, $\mathrm{E = W}$; work equals force multiplied by distance, $\mathrm{W = Fm}$ ; force equals mass multiplied by acceleration, $\mathrm{F = MA}$; and ...
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1answer
49 views

Finding 1/V from absorbance in Lineweaver-burk plot

I’ve got six test-tubes with $0.5\ \mathrm{ml}+0.5\ \mathrm{ml}$ of 0.005 %, 0.0025 %, 0.00125 %, 0.000625 %, 0.0003125 % and 0.0003125 % starch and 4.2 pH phosphate buffer solution (2, 4, 8, 16, and ...
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1answer
35 views

Inferring rate of reaction from time taken [closed]

Can the time taken be used to infer the rate of reaction? Here's an inline link to google
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2answers
108 views

Chemical kinetics of a reversible reaction

I am having trouble with the following question: Consider the following reversible reaction in which the reaction is first order in both directions: $$\ce{[A] <=> [B]}$$ $k_a$ is the rate ...
3
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1answer
43 views

Mechanisms in kinetic reactions

In my book is given the mechanism of $\ce{HBr}$ forming and I understand every step of it. We did the calculations of the rate of each reaction, which is easy depending on the sign (-,+) of compounds ...
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1answer
93 views

How is the “quasi-steady-state” assumption of Michaelis-Menten kinetics different from the steady state assumption of ordinary kinetics?

In Wikipedia's article for Michaelis-Menten kinetics, it titles the "[ES] = constant" section the "Quasi-steady-state approximation". Lehninger's Principles of Biochemistry, 4th Ed. pp. 203ff call ...
2
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1answer
34 views

Activated complex theory vs. consecutive reactions [duplicate]

Activated complex theory, tells us that due to the collision between the molecules of the reactants, they form a transition specie before the product is formed, which is called active complex. On the ...
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1answer
39 views

Order of reactions in kinetics

In kinetics, zero order reactions are those reactions who are independent from the concentration of the reactant or the product. So their rate is equal to the constant k. But still we build the ...
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1answer
25 views

Importance of unit of time used in rate law problem

If doing a problem where you use the integrated rate law for a second order reaction ($\frac{1}{[\mathrm{A}]}-\frac{1}{[\mathrm{A_0}]}=kt$) to first find $k$, then use that to find the halflife, does ...
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1answer
43 views

Activation energy and temperature

It is said that activation energy does not change with temperature. But I am unable to figure out why. If we increase the temperature, the kinetic energy of the molecules will increase and they will ...
2
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1answer
45 views

how to depict answer from this graph

i am talking about the 65th question, in the below given uploaded photo, i.e. the first order decomposition curves as per the given reaction for every mole of A3 decomposed, there is a liberation ...
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29 views

Rate Kinetics(suggested mechanisms)-Chemistry [closed]

http://maxpapers.com/wp-content/uploads/2012/11/9701_w14_qp_41.pdf question 1C) The compound nitrosyl fluoride, NOF, can be formed by the following reaction. \[\ce{2NO(g) + F2(g) <=> ...
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2answers
79 views

Why must the rate law be experimentally determined?

I am familiar with the idea that rate law must be determined experimentally. I am also familiar with the idea that there is no formulated way for coming up with the rate law besides just ...
2
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0answers
32 views

Find the equilibrium constant

In a container with volume 4 litres we have 2 moles $\ce{COCl2}$ and 4 moles $\ce{Cl2}$. Equilibrium is achieved when 60 % of the reactant $\ce{COCl2}$ is wasted 60 %. What is the equilibrium constant ...
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2answers
72 views

Given a forward reaction with positive enthalpy, is its reverse reaction be endothermic or exothermic?

I'm pretty sure the sign changes. But, I want to be sure if it becomes endothermic or exothermic.
2
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1answer
28 views

Accelerated Oxidation Of Iron When Coating Breaks

I was presented with the following information: If iron is painted, then oxygen and water are prevented from contacting the metal, and corrosion is avoided. Sometimes the iron is coated with a thin ...
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1answer
73 views

How to calculate the temperature at which a reaction becomes spontaneous?

At $25~^\circ\mathrm{C}$, $298~\mathrm{K}$,, the reduction of copper(I) oxide, $ \Delta H = 58.1~\mathrm{kJ}$, $\Delta S= 165~\mathrm{J/K}$, is nonspontaneous, $ \Delta G = 8.9~\mathrm{kJ}$. ...
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1answer
59 views

Molar heat of fusion of ice?

The molar heat of fusion of ice is 6.01 kJ/mol. Can you explain what this means? What I think it means is that it requires 6.01 kJ to melt a mole of ice. I'm not positive though..
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97 views

Calculate the number of moles of NO₂ (g) produced per hour per liter of air?

A reaction of importance in the formation of smog is that between ozone and nitrogen monoxide described by $\ce{O3(g) + NO(g)->O2(g) + NO2(g)}$ the rate law for this reaction is: rate of ...
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69 views

Rate constants for water exchange

Are rate constants for water exchange of transition metal aqua-complexes tabulated anywhere ? I haven't been able to find a resource which is anywhere near comprehensive.
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4answers
69 views

Justify assuming first-order kinetics for a complex

For the hydrolysis of $\ce{\mathit{trans\hyphen}[Co(en)2Cl2]Cl}$ (and cis) we measured reaction rates via spectrophotometry. Plots of change in absorbance $(\ln(A-A_\infty))$ were used to determine ...
2
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1answer
41 views

Suggest a method, other than spectrophotometry, for determining the reaction rate

For the hydrolysis of $\ce{\mathit{trans\hyphen}[Co(en)2Cl2]Cl}$ (and cis) we measured reaction rates via spectrophotometry. Plots of change in absorbance were used to determine the rate law and the ...
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1answer
52 views

Which species can't appear in the rate expression for this reaction scheme?

The answers are apparently F and G, but I don't see why D and E couldn't also be valid (considering the first step is the slowest). A and B will inevitably be in the rate equation since they are ...
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1answer
98 views

Representing woody biomass concentration for kinetic reactions

Woody biomass is composed of cellulose, hemicellulose, and lignin components. The following diagram provides representative formulas for each component: Biomass can be represented by it's density, ...
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3answers
59 views

Integration of the first order rate equation

Given the simple first order reaction $\ce{A -> P}$ derive the integrated rate law. $$\frac{d[A]}{dt} = -k[A]$$ Collect terms: $$\frac{d[A]}{[A]} = -kdt$$ Now for the bit I need help with, the ...
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1answer
125 views

Experimental difficulty with the iodine clock reaction

I did the iodine clock reaction using sodium metabisulfite and potassium iodate. As I understand it, increasing concentration is supposed to speed up your reaction rate. I did 10 trials. The first 5 I ...
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1answer
108 views

Relative energies between reactants and products

I've been asked to draw a relative energy sketch of the reactants and the two products. The reaction being examined was adding copper acetate monohydrate to glycine in two different fashions to create ...
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1answer
28 views

Sequential Kinetics

I was solving some problems on chemical kinetics, then I was just struck at some ques of sequential reaction kinetics. Given reactions $$\ce{O_3 + Cl \rightarrow O_2 + ClO ~~~ k_1=5.2 \times ...
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1answer
71 views

Calculate species concentration from first-order kinetic reactions

I am trying to determine the concentration of products from the kinetic reactions of wood pyrolysis. The kinetic scheme separates the wood into cellulose, hemicellulose, and lignin. For example, the ...
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1answer
80 views

How does a catalyst affect the rate equation

If I determine the order of the reactants in a reaction without using a catalyst, and then use a catalyst, will the order of the reactants then be different?
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1answer
50 views

Is there a list of known rate laws for reactions?

I've been scouring the web for a website/pdf that lists reactions and their corresponding rate laws. Something like: \begin{align} \ce{A + B &-> C} & ...
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41 views

Convert kinetic rate constant into a rate?

Can anyone tell me how I can convert a rate constant derived from first order kinetics (units are $\mathrm{h^{-1}}$) into an actual rate (turnovers/h)? The scenario is that I know my rate constant ...
2
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1answer
58 views

Kinetics: Order of Reaction

I am confused as to how an order of a reactant (n or m) in the rate law can be negative. This means that increasing the concentration of a reactant would actually decrease its rate of disappearance. ...
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1answer
151 views

Conc. vs Time Graph for Second Order Reaction

From my understanding plotting the conc. over time for a 0-order reaction yield a negative linear slope. Plotting conc vs time for a first order reaction intuitively yields an exponential type slope. ...
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1answer
36 views

Finding molarities of individual reagents given the chemical equation and total concentration in a container

I am given a table that gives me the different total pressures at certain times. The decomposition of phosphine is the reaction: $$\ce{4 PH3(g) <=> P4(g) + 6 H2(g)}$$ The time/pressure ...
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2answers
56 views

How to Determine the Rate Law knowing time and concentrations

Consider the hypothetical reaction described by the following equation: $$\ce{3 A + 2 B -> C}$$ Reagent B was added in excess and the following time concentration data was obtained. ...
2
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1answer
34 views

kinetic and thermodynamic parameters of biodiesel production from lard

I want to know if someone has experimental results and calculations of the kinetic and thermodynamic parameters of Base Catalyzed Transesterification of pig fat, if not which is the method used to ...