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. M

    Kinetics of bromide-bromate reaction

    Homework Statement The aim of my exercise is to explore the kinetics of the reaction between bromide and bromate (V) ions in acid solution as shown below: 5Br– + BrO3– + 6 H+ → 3 Br2 + 3 H2O (Reaction 1) To do this,To do this, a fixed amount of phenol (C6H5OH) and the...
  2. M

    Help with Chemistry Kinetics: Half-Life Calculation

    Need Help!-Chemistry kinetics [b]1. Consider the following initial rate data for the decomposition of compound AB to give A and B: [AB]o(mol/L) Initial Rate(mol/L*s) .200 3.20*10^-3 .400 1.28*10^-2 .600...
  3. M

    Solving Chemical Kinetics Homework for A, B, C & D

    Homework Statement Write down the material balance for the components A, B, C, D id this reaction takes place in a batch reactor: A+B\UpdownarrowC and C+B\UpdownarrowD The difunctional starting material (A) combines with the primary reactant (B) to form a monofunctional intermediate (C)...
  4. P

    How Do You Calculate Fractional Saturation in Enzyme Kinetics?

    Homework Statement Using the scheme below, define the fractional saturation of individual IPTG binding sites, YPI, and the fractional saturation of the dimer with operator DNA, YP2O in terms of the concentrations of intermediate dimer species. This Adair-like mass action scheme can be...
  5. A

    Solving Kinetics Questions: Two Cars Traveling on a Highway

    Homework Statement Two cars travel in the same direction along a straight highway, one at a constant speed of 55 mi/h and the other at 65 mi/h. (a) Assuming that they start at the same point, how much sooner does the faster car arrive at a destination 10 mi away? ______ min (b)...
  6. G

    Enyme Kinetics: Carbonic Anhydrase

    Homework Statement A carbonic anhydrase can generate H+ at a rate constant (Kcat) of 106 s-1. 1) What will be the pH in the solution after 0.1 nM of this carbonic anhydrase was incubated with unlimited substrate (CO2) for 1 min (assume the initial pH = 7.0)? 2) What will be the pH in...
  7. M

    Soup Can Kinetics: Calculating Accelerating Force

    Homework Statement mass of can .298 kg length of table 1.257 m height of elev .05m time trial 1 3.50 sec 2 4.22 sec 3 4.23 sec length of table determine the force required to accelerate the can along the table. avg speed is .36 m/s final speed is .72 m/s...
  8. dontdisturbmycircles

    Kinetics Question (Dependant motion, gravity, pulleys)

    I am in second year engineering and am trying very hard in this course. I just started doing problems regarding simple kinetics this morning and I am getting a lot of wrong answers. Originally I just claimed to myself that I had made simple math errors but understood the concepts. The math in...
  9. C

    Exploring Thermodynamics, Kinetics & Particles

    is it possible to make something 0 kelvin? and if you did this would it make that particle or group of particles have no motion or kinetic energy? do particles naturally want to move or is that influenced by thermodynamics (heat)? if photons cause light and they are described as an elementary...
  10. P

    How Do You Calculate Km in Multi-Step Enzyme Kinetics?

    The problem asks to consider the following reaction: S + E =ES1=ES2---> P + E where = between S + E and ES1 has a forward reaction constant of k1 and a reverse constant of K2. The = between ES1 and ES2 has a forward reaction of k3 and a reverse of k4 and ----> has a k5 forward reaction...
  11. V

    Arrhenius Equation - Chemical Kinetics

    Hello everyone, I am having trouble with determining where I erred in the following exercise. If someone could point out my mistake, I would appreciate the help. Thank you! --- 1. The decomposition of N2O5 has an activation energy of 103 kJ/mol and a frequency factor of 4.3E13 s^-1 . What...
  12. L

    Kinetics: Initial rates method

    In the iodine clock reaction involving persulfate and potassium iodide: why is the experimental method of determining rate law called 'method of initial rates' when acutally the 'average' rate is measured? How does 'intial' come into play? From what I've read it is because you're 'supposed' to...
  13. E

    Calculating Decay Events in Vintage Wine from 1946 using Tritium Kinetics

    1. surface water contains enough tritium to show 5.5 decays events per minute per 100. g of water. Tritium has a half-life of 12.3 years. You are asked to check a vintage wine that is claimed to have been produced in 1946. How many decay events per minute should you expect to observe in 100.g of...
  14. O

    Solving Rotational Kinetics Homework: Angular Acceleration of Flywheel

    Homework Statement The flywheel of a steam engine runs with a constant angular speed of 176 rev/min. When steam is shut off, the friction of the bearings and the air brings the wheel to rest in 2.8 hours. What is the magnitude of the constant angular acceleration of the wheel? (Use units of...
  15. S

    Kinetics of a Particle: Work and Energy

    Homework Statement The cyclist travels to a point A, pedaling until he reaches a speed Va = 4m/s. He then coasts up freely the curved surface. Determine how high he reaches up the surface before he comes to a stop. Also, what are the resultant normal force on the surface at this point and his...
  16. K

    Kinetics of acid-based and alkali-based catalysed reactions of esters

    Homework Statement Why is the acid based catalysed reaction of esters first order while the akaline based catalysed reaction is second order. Homework Equations rate is proportional to [ester]^a [water]^b The Attempt at a Solution i know that a fisrt order is proportional to...
  17. E

    Kinetics: Defining Temperatures for Molecular Energy Storage Modes

    When can you define temperatures for the molecular energy storage modes (i.e. translational, rotational, vibrational)? I have seen the graphs of this where translational modes are at room temperature and then as temperature increases, the rotational and later vibrational modes are "activated."...
  18. D

    How Can Biomineralization Kinetics Influence Bone Regeneration?

    Good afternoon everyone. I hope everyone is enjoying the holidays. I'm interested in studying the crystallization kinetics of several different calcium phosphate phases nucleating and growing on polymeric scaffold materials. The scaffolds are meant for use in different tissue engineering...
  19. T

    Enzyme Kinetics: Understanding Basic Concepts and Relevant Equations

    Homework Statement Hi, having not studied biology I'm struggling to get to grasps with what are probably basic concepts. Looking through the notes i have i was just wondering if the equations/derivations i'v attached are relevant, and if so how. A link to the powerpoint file can be found...
  20. L

    Solve Calc-Based Kinetics Problem: Initial Velocity for Washington Monument

    Homework Statement With what intial velocity must an object be thrown upward (from ground level) to reach the top of the Washington Monument (approx 550ft)? Homework Equations Here's what I know: s(0)=0 a(t)=-32ft/s^2 s(t_{max})=550\\ s'(t_{max})=0 The Attempt at a Solution...
  21. K

    Chemical Kinetics - Rate Laws and Mechanisms

    Homework Statement This is straight off an old AP Exam, but I can't seem to find it online so I'm hoping you all can help me out. 2 NO(g) + Br2(g) --> 2 NOBr(g) The following results were obtained in experiments designed to study the rate of the reaction above. Experiment Initial...
  22. S

    Kinetics of particles (Energy)

    1. A 100 kg satellite is placed in a circular orbit 3500 km above the surface of earth. At this elevation the acceleration of gravity is 4.09m/s_{2}. Determine the kinetic energy of the satellite , knowing that its orbitial speed is 22.9 x10_{3}km/h The answer:30.3 GJ ===== I have drawn...
  23. 9

    Rigid Body Kinetics Homework Solution

    Homework Statement The problem is shown in the attachment. Homework Equations Mo = Ia MgL/2 = moment of inertia of the bar Io = Ig + md^2 parallel axis theorum The Attempt at a Solution I found the moment of inertia of the bar about its center of mass: MgL/2 = (4.6*9.81*1.3)/2...
  24. K

    How Does First-Order Kinetics Affect Reactant Concentration Over Time?

    Homework Statement The initial concentration of reactant in a first-order reaction is 0.75M. The rate constant for the reaction is 2.75/s. What is the concentration (mol/L) of reactant after 6.5s? Homework Equations -kt=[A]initial/[A]anytime The Attempt at a Solution...
  25. P

    Colloidal Kinetics: Fick, Einstein & Stoke's Laws

    Hi! I want to make sure I have the right handle on this. Fick's law relates to dispersING solids, whereas Einstein's law of diffusion indicates disperSED particles, Stoke's law illustrates sedimentation and D=kT/6πηNa=RT/6πηaN is the overall equation relating all of the above to...
  26. Y

    Kinetics Homework Help: N2O5 Decomposition @ 70°C

    Hi everyone I need some help with this problem - The first order rate constant for the decomposition of N2O5 at 70 degrees celsius is 6.82x10-3 s-1 2N2O5 -> 4NO2 +O2 Suppose we start with 25 mmol of N2O5 in a volume of 2L. How many mmol of N2O5 will remain after 2.5 min? I'm not...
  27. B

    How Is the Initial Velocity of Ball B Calculated in Kinetics Problems?

    Hi everyone, I have a difficulty of the following Dynamics (kinetics) problems (from Hibbeler’s Eng Mech Dynamics, 11E book) PROBLEMS 12-26 Ball A is released from rest at a height of 40 ft at the same time that a second ball B is thrown upward 5 ft from the ground. If the balls pass one...
  28. B

    Molecule Kinetics: Calculating Temperature from Speed Upon Moon Re-Entry

    Homework Statement A space vehicle returning from the Moon enters Earth’s atmosphere at a speed of about 4.9E4 km/h. Molecules (assum nitrogen) striking the nose of the vehicle with this speed correspond to what temperature? Homework Equations KE=0.5mv^2=kT k: constant The Attempt...
  29. T

    Finding the Correct Force for Acceleration in Kinetics of Translation

    Homework Statement A 200kg body is supported by wheels @ B to roll freely w/o friction & by a sled @ A with which uk = 0.5. Compute the value of P to cause an acceleration of 0.02g. (g=9.8m/s^2) NOTE: Image not drawn to scale. http://www.geocities.com/timothybridge/kinOftrans.JPG...
  30. J

    Kinetics of metals reacting with acids

    hey. I am doing an investigation into reactions of acids with Mg. Firstly, iv investigated how order with respect to the acid varies for different acids i found that the orders for each of the acids are: Hydrochloric acid: 2 Sulphuric acid: 1 Phosphoric acid: 1.8 in an article, it said that...
  31. S

    Rotational Kinetics hardest problem

    Multiple-Concept Example 7 explores the approach taken in problems such as this one. The blades of a ceiling fan have a radius of 0.375 m and are rotating about a fixed axis with an angular velocity of +1.95 rad/s. When the switch on the fan is turned to a higher speed, the blades acquire an...
  32. G

    Basic Kinetics Question [Secondary]

    Okay I suck at physics and if someone could help me out it would be greatly appreciated. A ball is projected horizontally from the edge of a table which is 0.8 m high, as shown below. The ball lands 0.2m from the table How long does the ball take to fall to the ground? Worked it out to be...
  33. F

    Identifying Intermediates in chemical kinetics

    Hello, I have the following mechanism: NO + NO -> N2O2 and N2O2 + H2 -> N2O + H2O We need to identify intermediates in the mechanism. I have no idea how to do that. In case it helps, here are the answers (not sure they are right, but I think they are) to previous questions in the...
  34. F

    How do I solve these Chemical Kinetics homework problems?

    Hello everyone, I have been working on several exercises for the past several days, and there are some I just can't seem to do. I would appreciate some help! =) 1) We have the following reaction: C2H5Br (alc) + OH(-) (alc) --> C2H5OH (l) + Br(-) The (-) indicates it's an ion. The...
  35. I

    Understand Kinetics Modeling Equations/Derivation

    In a paper, I encountered a system modeled by six coupled first-order differential equations like so: \frac{dm_i}{dt}=-m_i+\frac{\alpha}{1+p^n_j}+\alpha_0 \frac{dp_i}{dt}=-\beta(p_i-m_i) , where i=1,2,3 and j=3,1,2. According to the paper, the system has a unique steady state which becomes...
  36. V

    Kinetics in Nromal and Tangential coordinates - SPINING ROD W/ SPOOL

    Kinetics in Nromal and Tangential coordinates - SPINNING ROD W/ SPOOL The 2-kg spool fits loosely on the inclined rod for which the coefficient of static friction is \mu_s\,=\,0.2. If the spool is located 0.25 m from A, determine the maximum speed the spool can have so that it does not slip up...
  37. S

    How Does a 10°C Temperature Increase Double the Rate of a Slow Reaction?

    We are currently studying reactions in terms of kinetic energy, reaction rates, collision theory, and so on. There is a question on my assignment that is kind of boggling me right now: An increase in temperature of 10 C rarely doubles the kinetic energy of particles, and hence the number...
  38. T

    What is the difference between sliding and rolling of a wheel?

    can anyone pls explain to me what is sliding and rolling of a let say a wheel??I'm really confuse about it thanx
  39. E

    A Couple of Kinetics Questions

    I am completely stuck on a couple of questions and would like a bit of help on these. First one. This I have no idea where to even start and I can't find anything on it in my text either. So maybe a formula or point me in the right direction would help.:biggrin: Calculate the fraction of...
  40. G

    Speed of the molecules on the gas kinetics theory

    How we can face the speed of the molecules on the gas kinetics theory and the speed barrier of light ? because v=sqrt(3kT/m) were k is boltzman T = kelvin and m = mass of the element remember the huge T of the big bang
  41. K

    What was the average force applied to the box in the direction of motion?

    A 7 kg box increases its speed form 2 to 4 m/s over a horizontal distance of 5 meters. coefficient fo kinetic friction is .1. what was the average force applied tothe box int he direction of the motion?
  42. O

    Kinetics of an iodine clock reaction?

    kinetics of an iodine clock reaction? i am currently writing up my lab report (from a week ago, i know, i should do it straight away...) on the kinetics of an iodine clock reaction and am calculating the order of the reaction and have taken a wrong turn in my calculations. instead of going...
  43. I

    Reaction kinetics question

    I'm really having trouble with this question, can someone help me with an explanation? Is it possible to vary the factors of concentration, surface area, and temperature in a way that would prevent a reaction from happening? explain your answers in terms of collisions. Will catalysts...
  44. A

    Reaction Kinetics: Heterogenous vs Homogenous - 65 Characters

    would reactions happen faster in heterogenous rxns or in homogenous? also, i was wondering if i am correct in assuming that heterogenous & homogenous reactions affect: temp, concentration, nature of reactants and catalysts? only surface area affects heterogenous. for this question, would u...
  45. E

    Help Needed: Activation Energy for KMnO4 + H2C2O4 Reaction

    Plea for help with kinetics lab -- Urgent I am trying to find a value for the activation energy of the reaction involving potassium permanganate and oxalic acid. I have scoured every free chemistry database on the internet and come up with nothing. Does anyone know how I can calculate this...
  46. E

    Need help with chemistry lab - kinetics

    need urgent help with chemistry lab - kinetics Where can I obtain the accepted value for the activation energy of the reaction involving potassium permanganate and oxalic acid? I did the first part of the lab, which involved finding the rate law experimentally, correctly. But I ran out of...
  47. maverick280857

    Chemical Kinetics Query

    HI While working on some chemical kinetics problems, I came across the statement, the fraction of activated molecules is 10^{-15} in a problem where some other constants were also provided and the half life was to be found (for a first order reaction). My specific query is: Is this...
  48. Link

    Quick Chemical kinetics question

    The rate constant for a certain reaction has the units concentration/time. What is the order of the raction? A. 0 B. 1 C.2 D.3 My reasoning: K = [A]^m x [B]^n Since the concentration/time is to the power of one, both m and n must be one i think which give an overall order of...
  49. J

    Investigating the Kinetics of a Steel Ball Rolling on a Level Surface

    A steel ball has a mass of 4 kg and rolls along a smooth level surface at 62 m/s. a) Find its kinetic energy ( i found this.. ) b) At first, the ball was at rest on the surface. A constant force acted on it through a distance of 22 m to give it the speed of 62 m/s. What was the magnitude...
  50. R

    How Is the Michaelis-Menten Equation Applied in Enzyme Kinetics?

    Hey, I'm a newbie here. :smile: Just wanted to say this is a really great site. Lots of informative stuff! Anyway, my midterm is coming up and I'm having trouble grasping enzyme kinetics. I'm familiar with the Michaelis - Menten equation, but I don't know how this equation is applied since...
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