reaction kinetics
DESCRIPTION
Reaction Kinetics. The rate at which a reaction occurs. Kinetic Energy. Related to molecular speed KE= ½ mv 2 Higher velocity (faster)= higher energy. Reaction Rate. The rate of reaction tells the speed at which the reaction takes place. Collision Theory. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/1.jpg)
Reaction KineticsThe rate at which a reaction occurs
![Page 2: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/2.jpg)
Related to molecular speed KE= ½ mv2
◦ Higher velocity (faster)= higher energy
Kinetic Energy
![Page 3: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/3.jpg)
The rate of reaction tells the speed at which the reaction takes place
Reaction Rate
![Page 4: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/4.jpg)
Collision Theory states that atoms, ions, and molecules must collide in order to react
Collision Theory
![Page 5: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/5.jpg)
Not every collision between atoms and molecules results in a reaction!
1. Orientation is critical! 2. They must collide with sufficient energy
(the activation energy)
Collision Theory
![Page 6: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/6.jpg)
CO (g) + NO2 (g) CO2 (g) + NO (g)
![Page 7: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/7.jpg)
Any change that increases the number of collisions should increase the reaction rate
Collision Theory
![Page 8: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/8.jpg)
Factors in reaction rates…
![Page 9: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/9.jpg)
What are their tendencies towards bond formation?◦ Cs + H2O -----> CsOH + H2
Instantaneous◦ Cs very reactive(low IE, EN)◦ Fe + H2O -----> Fe2O3+ H2
very slow
1. Nature of the reactants
![Page 10: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/10.jpg)
Reactions usually occur in liquid, gas, or aqueous phase
Related to surface area◦ Higher surface area means faster reaction in
heterogeneous reactions Reactions only occur at phase interface
2. The ability of the reactants to meet (collide)
![Page 11: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/11.jpg)
Often listed as molarity (mol/L) Written as square brackets [ ]
◦ The moalrity (concentration) of HBr= [HBr] More reactants = more collisions More collisions = increases reaction rate
3. Concentration of the reactants
![Page 12: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/12.jpg)
Temperature is a measure of average kinetic energy
Higher T means higher KE Faster moving molecules means more
collisions More collisions means a faster reaction rate
4. Temperature
![Page 13: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/13.jpg)
4. Temperature
![Page 14: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/14.jpg)
Increases the reaction rate without being consumed in the process
Lower the energy needed to react (Ea)
5. Catalyst
![Page 15: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/15.jpg)
Lower activation energy means more collisions between particles have sufficient energy to react.
5. Catalyst
![Page 16: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/16.jpg)
A heterogeneous catalyst exists in a physical state different than that of the reaction it catalyzes.
A homogeneous catalyst exists in the same physical state as the reaction it catalyzes.
A reforming catalyst is consumed in the reaction, but then re-made
An enzyme is a biologically active catalyst An inhibitor slows down a reaction by
increasing the activation energy
5. Catalyst
![Page 17: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/17.jpg)
1. Nature of the reactants2. The ability of the reactants to collide3. The concentration of the reactants4. The temperature5. Catalysts
To review….
![Page 18: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/18.jpg)
Now with numbers…
![Page 19: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/19.jpg)
A rate is something per unit of time◦ interest rate = $ earned / time ◦ speed = distance traveled/ time ◦ pay = dollars / hour
Measuring rates
![Page 20: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/20.jpg)
as the reaction proceeds, the reactants are “used up”
[reactants] goes down [products] goes up Reaction rate is measured as :
◦ Δconcentration /Δtime •(mol/L)/s, M/s, or mol L-1s-1
Measuring reaction rates
![Page 21: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/21.jpg)
Graphing ΔM
![Page 22: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/22.jpg)
The coefficients of a chemical equation give us some insight as to the relative rates of consumption of reactants and production of products, but not “absolute” amounts.
Coefficients and Rates
![Page 23: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/23.jpg)
It takes 2 A’s for every single B that reacts, so A is “disappearing” twice as fast as B is
2A + B 3C + 2D
![Page 24: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/24.jpg)
There are 2 D’s produced for every B and every 2 A’s that are “consumed”, so D is appearing at the same rate A is disappearing and twice as fast as B is disappearing
2A + B 3C + 2D
![Page 25: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/25.jpg)
C is being produced 3 times faster than B is being used up, and 3/2 times faster that A is being used up
2A + B 3C + 2D
![Page 26: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/26.jpg)
A Rate Lawis an equation that describes how a change in concentration affects the reaction rate.◦ for the reaction A + B products◦ The rate law would be: ◦ rate = k[A]m[B]n
Rate Law
![Page 27: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/27.jpg)
rate = k[A]m[B]nk= the rate constant depends on the
temperature, different for each reaction
m= the “order of reaction” with respect to A
n= the “order of reaction” with respect to B
Rate Law
![Page 28: Reaction Kinetics](https://reader035.vdocument.in/reader035/viewer/2022081421/5681642b550346895dd5ee4f/html5/thumbnails/28.jpg)
rate = k[A]m[B]n m and n have to be experimentally
determined; they are not the same as the reaction coefficients except by coincidence.
Rate Law