Spontaneity


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905373636
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Spontaneity

Postby 905373636 » Fri Feb 21, 2020 1:37 pm

Do higher cell potentials within a cell indicate anything about the rate of the reaction or just the spontaneity?

Ronak Naik
Posts: 103
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Re: Spontaneity

Postby Ronak Naik » Fri Feb 21, 2020 1:45 pm

Higher cell potentials will indicate a greater level of spontaneity; however, spontaneity is a thermodynamic concept. It does not relate to kinetics, and thus, will not tell us anything about the speed of a reaction.

Chris Tai 1B
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Re: Spontaneity

Postby Chris Tai 1B » Fri Feb 21, 2020 10:48 pm

Spontaneous processes don't necessarily happen quickly, it just means that over time there is a tendency for that reaction to occur.
The equation that relates spontaneity to the cell potential difference is deltaGknot = -nFEknot. This makes sense, because the more positive the E value of cell potential is, the battery is able to convert more energy to do electrical/chemical work, and because there is a negative sign, the value of deltaGknot will be more negative. Hence, the reaction as a whole will be more negative, and have a spontaneous nature. The opposite is true if the value of E is negative.

DHavo_1E
Posts: 118
Joined: Sat Aug 17, 2019 12:17 am

Re: Spontaneity

Postby DHavo_1E » Sun Feb 23, 2020 7:56 pm

Chris Tai 1B wrote:Spontaneous processes don't necessarily happen quickly, it just means that over time there is a tendency for that reaction to occur.
The equation that relates spontaneity to the cell potential difference is deltaGknot = -nFEknot. This makes sense, because the more positive the E value of cell potential is, the battery is able to convert more energy to do electrical/chemical work, and because there is a negative sign, the value of deltaGknot will be more negative. Hence, the reaction as a whole will be more negative, and have a spontaneous nature. The opposite is true if the value of E is negative.


Hello,

What does it mean when E is positive or negative? Thank you!

Angela Wu-2H
Posts: 50
Joined: Fri Aug 30, 2019 12:16 am

Re: Spontaneity

Postby Angela Wu-2H » Sun Feb 23, 2020 7:58 pm

Ronak Naik wrote:Higher cell potentials will indicate a greater level of spontaneity; however, spontaneity is a thermodynamic concept. It does not relate to kinetics, and thus, will not tell us anything about the speed of a reaction.


So then what tells us about the speed of a reaction? Is it just a catalyst?

305385703
Posts: 102
Joined: Thu Jul 11, 2019 12:15 am

Re: Spontaneity

Postby 305385703 » Sun Feb 23, 2020 8:13 pm

Cell potential has nothing to do with reaction speed, although there are other factors that can speed up a reaction with a large cell potential. Think of it as the distance in energy between the products and reactants.

VLi_2B
Posts: 99
Joined: Sat Sep 14, 2019 12:15 am

Re: Spontaneity

Postby VLi_2B » Sun Feb 23, 2020 8:39 pm

DHavo_1E wrote:
Chris Tai 1B wrote:Spontaneous processes don't necessarily happen quickly, it just means that over time there is a tendency for that reaction to occur.
The equation that relates spontaneity to the cell potential difference is deltaGknot = -nFEknot. This makes sense, because the more positive the E value of cell potential is, the battery is able to convert more energy to do electrical/chemical work, and because there is a negative sign, the value of deltaGknot will be more negative. Hence, the reaction as a whole will be more negative, and have a spontaneous nature. The opposite is true if the value of E is negative.


Hello,

What does it mean when E is positive or negative? Thank you!


If an electrode potential is negative that means it's donating electrons. If the electrode potential is positive it means that it is taking electrons.

Chris Tai 1B
Posts: 102
Joined: Sat Aug 24, 2019 12:16 am

Re: Spontaneity

Postby Chris Tai 1B » Mon Mar 02, 2020 1:09 pm

DHavo_1E wrote:
Chris Tai 1B wrote:Spontaneous processes don't necessarily happen quickly, it just means that over time there is a tendency for that reaction to occur.
The equation that relates spontaneity to the cell potential difference is deltaGknot = -nFEknot. This makes sense, because the more positive the E value of cell potential is, the battery is able to convert more energy to do electrical/chemical work, and because there is a negative sign, the value of deltaGknot will be more negative. Hence, the reaction as a whole will be more negative, and have a spontaneous nature. The opposite is true if the value of E is negative.


Hello,

What does it mean when E is positive or negative? Thank you!


If E is a positive value, then there is a positive difference in cell potential, which means there's potential for the cell to do work. This phenomenon is favorable, and indicates that it is likey that electrons will flow in a redox reaction. If E is a negative value, then the opposite is true.


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