Kinetics vs thermodynamics

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Jina Kwon
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Joined: Fri Aug 09, 2019 12:15 am

Kinetics vs thermodynamics

Postby Jina Kwon » Fri Mar 13, 2020 11:10 am

What's the difference between kinetics and thermodynamics when controlling a reaction?

Shutong Hou_1F
Posts: 117
Joined: Sat Sep 14, 2019 12:17 am

Re: Kinetics vs thermodynamics

Postby Shutong Hou_1F » Fri Mar 13, 2020 12:12 pm

Kinetics describes the pathway of reactions, with an emphasis on the activation energy that signifies the energy difference between the free energy of reactants and the transition state. Kinetic analysis is about the speed or rate of reaction, using experimental techniques to observe reactant & product concentrations. Thermodynamics studies the initial and final state, especially the initial & final Gibbs free energy, as well as entropy & enthalpy. Saying that a reaction is favorable/spontaneous doesn't imply that the reaction would occur at std or how fast the reaction would occur. Reaction order and rate constants are determined by experiment data and are independent of coefficients; however, the equations of equilibrium constants can be directly figured out by looking at chemical equations.

Chantel_2I
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Re: Kinetics vs thermodynamics

Postby Chantel_2I » Fri Mar 13, 2020 12:48 pm

Shutong Hou_1F wrote:Kinetics describes the pathway of reactions, with an emphasis on the activation energy that signifies the energy difference between the free energy of reactants and the transition state. Kinetic analysis is about the speed or rate of reaction, using experimental techniques to observe reactant & product concentrations. Thermodynamics studies the initial and final state, especially the initial & final Gibbs free energy, as well as entropy & enthalpy. Saying that a reaction is favorable/spontaneous doesn't imply that the reaction would occur at std or how fast the reaction would occur. Reaction order and rate constants are determined by experiment data and are independent of coefficients; however, the equations of equilibrium constants can be directly figured out by looking at chemical equations.

So if a reaction is spontaneous, meaning negative delta G, it won't happen freely if the activation energy is too high? I thought if delta G was negative it meant that the reaction would occur at that temperature without any added energy.

KeyaV1C
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Re: Kinetics vs thermodynamics

Postby KeyaV1C » Fri Mar 13, 2020 1:06 pm

Chantel_2I wrote:
Shutong Hou_1F wrote:Kinetics describes the pathway of reactions, with an emphasis on the activation energy that signifies the energy difference between the free energy of reactants and the transition state. Kinetic analysis is about the speed or rate of reaction, using experimental techniques to observe reactant & product concentrations. Thermodynamics studies the initial and final state, especially the initial & final Gibbs free energy, as well as entropy & enthalpy. Saying that a reaction is favorable/spontaneous doesn't imply that the reaction would occur at std or how fast the reaction would occur. Reaction order and rate constants are determined by experiment data and are independent of coefficients; however, the equations of equilibrium constants can be directly figured out by looking at chemical equations.

So if a reaction is spontaneous, meaning negative delta G, it won't happen freely if the activation energy is too high? I thought if delta G was negative it meant that the reaction would occur at that temperature without any added energy.


A negative delta g means a reaction will take place without added energy, but it doesn't imply anything about how quickly the reaction will happen. The reaction rate depends on the activation energy. I'm pretty sure reactions with high activation energies and a negative delta g can occur without an additional input of energy, but the temperature for the reaction to occur in that manner is usually too extreme to take place without a catalyst or added energy.


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