# What is Kinetics: Definition and 254 Discussions

Chemical kinetics, also known as reaction kinetics, is the branch of physical chemistry that is concerned with understanding the rates of chemical reactions. It is to be contrasted with thermodynamics, which deals with the direction in which a process occurs but in itself tells nothing about its rate. Chemical kinetics includes investigations of how experimental conditions influence the speed of a chemical reaction and yield information about the reaction's mechanism and transition states, as well as the construction of mathematical models that also can describe the characteristics of a chemical reaction.

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1. ### A Kirkendall effect: vacancy concentration and pair interaction energy

I am reading the following article on Kirkendall effect leading to the Formation of a hollow binary alloy nanosphere: a kinetic montecarlo study. I am unable to understand or find in references the reasoning to obtain equation (1):
2. ### What's the derivation of the 'Kinetic Equation' in Chemical kinetics?

Hi, I'm following an introduction course to chemistry and I am reviewing the chapter on Chemical kinetics. It's shown that the reaction speed for a certain component of a general chemical equation such as aA +bB <-> cC + dD , might be expressed as v = k[A]m[ B]m. I was wondering where it does...
3. ### Biology How Do Stoichiometric Coefficients Affect Reaction Rates?

Hi, I was attempting the following question and don't know how to find the 'reaction rate': "For the reaction the following stoichiometric coefficients have been determined: 2 ##C## react to form 2 ##E## and 1 ##F##. The rate of formation of E is ##1.6\times10^{–4} mol L^{–1} s^{–1}##. What is...
4. ### Point Kinetics for Linear Insertion of Reactivity

I want to use the point reactor kinetics equations to solve for the power as a function time when a reactivity of gamma*t is added to a reactor that is at equilibrium at time 0. I am also asked to consider the case where the transients are long-lived compared to the lifetime of prompt neutrons...
5. ### Rigid body kinetics -- force on ankle joint

PROBLEM Here from the conservation of angular momentum I found angular velocity just before impact, $$H_1 = 0$$ $$H_2 = I_0\omega + mV_0d$$ $$H_2 = 66\omega + 76.(1.2).(0.87)$$ $$H_1 = H_2$$ $$\omega = 1.202 rad/s$$ But I couldn't solve it to find joint force. Thanks in advance,
6. ### Exploring "Thermokinetics": What Is It?

Wikipedia https://en.wikipedia.org/wiki/Thermokinetics says that "thermokinetics" studies the rate of chemical decomposition, whereas a dictionary https://www.yourdictionary.com/thermokinetic gets no further than saying that it combines thermodynamics and kinetics, and a book on it...
7. ### (Conceptual- Planar Kinetics) How to maintain the position

Relevant equations : Kindly advise whether this approach is correct, I am not sure whether the friction force should be considered.
8. ### I Subquantum kinetics- anything to it?

Is there any evidence to support the idea of subquantum kinetics and alternative it provides to the Big Bang? Most publications which touch on it seem to link back to Dr. LaViolette so that seems odd to me. Has this idea been disproven or is there a chance this is a Continental Drift, Alfred...
9. ### Chemical kinetics lab question

last week i did a chemistry lab. i mixed NaOH 0.03M with equal part of methyl violet and mesured aborbance in a spectrophotometer. then i did the same thing with a 0.05M and methyl violet i did today the graphs and got the k' =-0.1647 for the first solution and k'=-0.4022 for the second...
10. ### Kinetics Problem: Head-On Collision Between Two Cars

Since the mass of both vehicles is the same, it's possible to calculate Ki which happens to be 512,5J and from there, multiply it by 0,25 since 75% of the energy is gone and I end up with 128,125J. Now my problem is that for the velocity, I have: 25,0 + -20,0 = V1 + V2 which is 5,00 = V1 + V2...
11. ### Reaction kinetics + Gillespie algorithm: Propensity function?

I'm trying to simulate a simple series reaction stochastically using Gillespie's algorithm. I found this file: What is this 'propensity function'? Say for example I have the simple reactions: A --(k1)--> R R--(k2)--> S are these 'propensity functions' the rates (a wild guess)? I mean; α1 =...
12. ### Analytical solution to mono-group kinetics with a ramp of reactivity

Consider the mono-group model and a ramp in reactivity like ##\rho = -\gamma \beta t## The system is $$\frac {dP}{dt} = \frac {\rho - \beta}{\Lambda} P + \lambda C$$ $$\frac {dC}{dt} = \frac {\beta}{\Lambda} P - \lambda C$$ 1st method: assume that the concentration of precursor doesn't...
13. ### Time needed for a Force F to accelerate the crate to 2m/s? (Dynamics)

So above is the question. The picture below is my attempt at the solution: However the answer at the back of the book suggest that T=1.929s
14. ### Need book recommendation to learn kinematics and kinetics

Hi I am trying to learn kinetics and kinematics: Euler angles Directional cosine matrices Quaternions Inertia tensors The usage of Jacobians in robotics Manipulator kinematics Eulers equations Newton-Euler equations etc My background is in mathematics, so I would like a book which takes a...
15. ### Exploring Euler's Formula in First Order Chemical and Nuclear Reaction Kinetics

Has anyone ever encountered a discussion on the topic of applying Euler's formula exp(i*x) = cos(x) + i * sin(x) to the equation governing first order chemical (and nuclear) reaction kinetics? d[Reactant]/dt = C*[Reactant]
16. ### How to calculate kinetics values?

Hello The table below shows some kinetics values for two types of the GOD enzyme, the free and the immobilised. How can I comprehend what these values mean? I want to know how many grams of substrate are 'converted' per sec per mg of enzyme. I assume the substrate concentration plays role so...
17. ### Question about simple kinetics and stoichiometry

Hi, I'm having trouble with this simple reaction (1): $$A + A → I$$ with ##R = kC^2_A## I'm assuming it takes place in a Batch reactor so the mass balance should yield: $$\frac {dC_A} {dt} = -2R = -2kC^2_A$$ But, as I recall (I should be wrong though)...
18. D

### Chemical Kinetics: velocity and equilibrium

Hi everybody, Given a generic reaction ## Reagents ↔ Products ## the velocity of the reaction is ##R = R_{right} - R_{left} ## To take in account that the velocity of the reaction will slow if approaching the equilibrium we say that $$R = R_{right}(1 - \frac K K_{eq})$$ Although it seems...
19. ### The path of the 3.6-kg particle P is an ellipse

Homework Statement 13.71 The path of the 3.6-kg particle P is an ellipse given by ##R = \frac {R_0} {(1+ecosθ)}##. where R_0 = 0.5m and e=2/3. Assuming that the angular speed of line OP is constant at 20 rad/s, calculate the polar components of the force that acts on the particle when it is at...
20. ### A package of mass m is placed inside a drum

Homework Statement 13.69 A packege of mass m is placed inside a drum that rotates in the vertical plane at the constant angular speed ##\dot {θ} = 1.36 rad/s##. If the package reaches the position θ = 45deg before slipping, determine the static coefficient of friction between the package and...
21. ### The pendulum is released from rest with θ = 30deg

Homework Statement 13.54 The pentulum is released from rest with θ = 30deg. (a) Derive the equation of motion using θ as the independent variable. (b) Determine the speed of the bob as a function of θ. The solutions given in the textbok are a) ##\ddot θ = -4.905sinθ rad/s^2## b) ##6.26\sqrt...
22. ### Calculate the angular velocity and angular acceleration (pendulum)

Homework Statement 13.53 The tension in the sting of the simple pendulum is 7.5N when θ=30deg. Calculate the angular velocity and angular acceleration of the string at this instant. Homework EquationsThe Attempt at a Solution Is this correct?
23. ### Banked Curve-Determine smallest static coefficient of friction

Homework Statement 13.49 The flatbed railway car travels at the constant speed of 80 km/h around a curve of radius 55m and the bank angle 15deg. Determine the smallest static coefficient of friction between the crate and the car that would prevent the crate of mass M from sliding. Homework...
24. ### Determine stopping distance of a train traveling at 20m/s

This is problem 12.81 from Pytels Dynamics 2nd edition 1. Homework Statement A train traveling at 20m/s is brought to an emergency stop. During braking, the acceleration is a=-(7/4)+(t/16) m/s^2, where t is the time in seconds measured from when the brakes were applied. (a) Integrate the...
25. ### Calculating Height h from a Projectile Launched at A

Homework Statement A projectile launched at A with an initial velocity of 24 m/s at the angle θ=60deg, impacts the vertical wall at B. Neglecting air resistance, calculate the height h Homework EquationsThe Attempt at a Solution Here is my solution As you can see to find height h I assumed...
26. ### Pytels Dynamics 12.39: A rocket is launched vertically

Homework Statement A 2000-kg is launched vertically from the surface of the earth. The engine shuts off after providing a constant propulsive force of 60 kN for the first 20 seconds. Neglect the reduction in the mass of the rocket due to the burning of the fuel and the variation of the...
27. ### Pytels Dynamics 12.35: A cart carrying a small package

Homework Statement The cart carrying the small 9-N package A is moving up the incline with constant acceleration α. If the package stays at rest relative to the cart in the position θ=45deg, determine the value of α. Neglect friction. Homework EquationsThe Attempt at a Solution [/B] Are my...
28. ### Reactor Design and Kinetics of Reactions

Homework Statement My problem deals with understanding why we substitute in the reaction kinetics equivalent into mass conservation equation instead of dealing with differentials Homework Equations From the conservation of mass law about an envelope: \frac{dm}{d t} = \sum m_{in} - \sum...
29. ### Kinetics question (Chemical engineering)

Hey! I have a question regarding this question that I have to answer. It is about the kinetics of a substance X whose product is 2Y. It is in Swedish and here is the translation: The absorbance of a 0,030M-solution of X was calculated with the help of a Spectrometer. The Spectrometer was...
30. ### Kinetics of System Particle/ Pulley system with masses and i

I can't seem to solve it, considering inertia can someone please solve it, both of the following question in the given picture. I would be very much thankful.
31. ### MCQ: Enzyme Kinetics - Find the Zeroth Order Answer

Homework Statement An enzyme catalysed reaction becomes zeroth order when: a.The velocity of enzyme action very low b. The velocity of enzyme action very high c.Enzyme conc very high d. All of these The attempt at a solution I understand An enzyme mediation recation becomes Zeroth order if [...
32. ### What equations are needed to solve this wheelchair kinetics problem?

Homework Statement A man is pushing the wheelchair having combined mass of 80kg with center of gravity at CG. The mass of each rear wheel is 1.6 kg and moment of inertia 0.1kgm^2. Friction coefficient for all wheels 0.6 . Find maximum acceleration of the wheelchair without slippage between the...
33. ### Reaction kinetics for ammonia

I need to design an ammonia production process but I can't find the kinetic info from the articles online. The catalyst will be iron. Can somebody explain how to find kinetics data and conversion rate? I found some articles but there was no conversion info on them.
34. ### Iodine Clock Kinetics: Which Mechanism is Supported?

1. Homework Statement An iodine clock kinetics experiment was performed by varying the composition of reactant solutions and measuring resulting rates of reaction (based on the data given, I have determined the rate law to be R = [I-]1[S2O82-]1). Which of these four proposed mechanisms below...
35. ### Fischer-Tropsch Conversion / Kinetics

Hi, We are currently working on a small-scale Fischer-Tropsch process. The modeling software we are using is HYSYS (Aspen). We want to produce X barils of oil / day using syngas (H2:CO ratio 2:1) using cobalt catalysts. The problem we are currently facing is that we do not have the kinetics...
36. ### I Energy Conversion With Supercritical Fluids

Technically, this isn't a question concerning supercritical fluids. It's more about converting thermal energy into velocity by playing "keep-away" with molecules that want to go supercritical. The idea is simple. In an fully contained system, we can more or less say volume is static...
37. ### [Kinetics] Using Rate as a Conversion Factor

Homework Statement Certain pollutants encourage the following decomposition of ozone: 2O 3(g) -> 3O 2(g), at a rate of 6.5 x 10-4 M O 3/s. How many molecules of O2 gas are formed in each litre of atmosphere every day by this process? (As this problem provides a rate in units of mol/L/s and...
38. ### Stuck with 2D kinetics problem

Homework Statement Hi, I've been trying to solve this exercise for the last four hours and I'm totally stuck. The problems goes like this: Given the mechanism in the image, located in the vertical plane, the OB cord is cut when t=0. Find the reactions Rx, Ry and N in {Kgf} for the instants...
39. ### What are the forces acting on a car on a slope at an angle of θ=33.2°?

Homework Statement Please refer to both figures. The result of the example problem was θ=33.2° Homework Equations ΣFn=man The Attempt at a Solution I am stumped. I thought you could solve the forces in the z direction, straight up from the car, and set that to zero since there is no...
40. ### Determining Rate Constant for Hydrolysis of Ethyl Lactate with Acid Catalysis?

Homework Statement Hydrolysis of ethyl lactate Determine the value of the rate constant for the hydrolysis of ethyl lactate from the following data. Mass of ethyl lactate (grams): 0.5956 Concentration of stock HCl solution (M): 0.01023 Standardization titration volumes (of NaOH): Run...
41. ### Solve Km with Alpha-ChymotrypsinHydrolysis & 4-Nitrophenyl Trimethylacetate

I did a practical and am now trying to do the data analysis of it. the prac was the alpha-chymotrypsin catalyzed hydrolysis of 4-nitrophenyl trimethylacetate. I have values for X, Y and B and the lab manual has asked "Using the approximated, simplified expressions for X (equation 2), Y (equation...
42. ### Kinetics with Pressure: Explanation & Derivation

This post is not about a homework problem but about a derivation When i was flipping through a physical chemistry book I found a formula which looked like How ever I am clueless to what it is Can anyone explain what it is for And possibly Derive it Thank you
43. ### Kinetics problem from olympiad

Homework Statement Homework Equations Is the question asking the concentration when the system has reached its half life Can use the half life formula?[/B]The Attempt at a Solution So 1/cT + 1/co = kt 1/(4 *10-2) + 1/x = k(half life time) Is this the right approach Please help me...
44. ### Reaction Kinetics, batch reactor varying volume

NO TEMPLATE BECAUSE THREAD WAS ORIGINALLY ENTERED INTO WRONG FORUM Hi Guys, I have attached the question that I am struggling with (part b of the question) I have worked out that the conversion of A is X=0.21 Using this conversion I'm trying to work out the time required for the reaction I...
45. ### Magnitute and Direction of Electric Field Based on Particle

Homework Statement A positively charged particle initially at rest on the ground accelerates upward to 180 m/s in 2.70 s .The particle has a charge-to-mass ratio of 0.100 C/kg and the electric field in this region is constant and uniform. What are the magnitude and direction of the electric...
46. ### What are some examples of kinetic equations and graphs in a kinetics course?

Hey guys, new here :biggrin: Just started a kinetics course and I'm looking forward to discuss the meanings and maybe get some examples of the kinetic equations and graph's I'll encounter (just finished the time distance stuff) pardon my newness to the world of physics, this would be my first...
47. ### Activation energy and pre exponential factor

Homework Statement Calculate activation energy and pre exponential factor, i need help with the pre exponential factor Homework Equations Temperature °C -20 = 253 k -10= 263 0=273 10=283 20=293 Rate const. s-1 1.15 3.85 11.3 28.7 74.0 The Attempt at a Solution i already plotted the graph on...
48. ### Solids and Liquids in Kinetics and Equilibrium

I just now read in my textbook that solids and liquids are not included in equilibrium expressions, are they included in rate laws? If not, why? Would a greater molar amount of solid or liquid increase the rate of reaction? And why isn't surface area included in Rate Laws? Also, for the...
49. ### Help with a mechanics problem from Kleppner's book

Homework Statement An elevator departs the ground at t=0 With uniform velocity. At T1 a boy drops a marbel through the floor of the lift that falls under constant acceleration g=9.8 ms^-2. If it takes marbel T2 time to fall down, what was the height at the T1. Homework Equations h=vT1 h= vT2...
50. ### Heat as Electromagnetic and Molecular Kinetics

Consider the image below Does it emit all 3 types of heat in the form of UV, IR and light? At what threshold does light start to appear and what colors should it illuminate? Hypothetically, say I have an induction furnace and is capable of setting frequencies to about 700THz, will it be able to...