Thermodynamically favored reaction

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In summary, the conversation is about the electrolysis of seawater and determining which reaction is thermodynamically favored. The two reactions being compared are the production of hydrogen and oxygen with a standard cell potential of -2.06 V, and the production of hydrogen and chlorine with a standard cell potential of -2.19 V. The question is whether the favored reaction is the one with a more negative voltage or the one with a smaller absolute value. The concept of thermodynamic favorability is discussed, and the name of the quantity that measures this is requested. The discussion also touches on how this quantity relates to variables in an electrochemical cell. The person asking the question is unsure about the meaning of "lower" voltage and if it refers to
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I have a homework question about the electrolysis of seawater, and I need to know what reactions are thermodynamically favored. One reaction is the production of H2 and O2, and it has a standard cell potential of -2.06 V. The other is the production of H2 and Cl2, and has a standard cell potential of -2.19 V. Is the favored reaction the one that occurs at a more negative voltage, or the one at a voltage with a smaller absolute value?
 
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  • #2
What does it mean for a reaction to be "thermodynamically favored"? What is the name of the quantity that measures this ? How does that quantity relate to the variables you have in an electrochemical cell?
 
  • #3
The production of hydrogen and oxygen from water is not favored thermodynamically so you can guess upon the productino of hydrogen and chlorine gas based on this.
 
  • #4
But based on the voltages which will be favored over the other? I know that reactions at "lower" voltage/ cell potential are favored, but what do they mean by lower? Is it the one with an actual lower number (more negative) or the one with a voltage closer to zero? I need to know for an exam tomorrow, not just for these particular reactions. Thanks!
 
  • #5
Doesn't your text say answer explicitly on these matters? I gave you hints in my post, and you should be able to figure it out.
 
  • #6
Ok so it's the more negative voltage that's favored.
My book didn't say, and my problem was that I got conflicting answers from different TAs. The answer sheet to the problem set also contradicts what you said, but they're wrong sometimes (quite often actually.)
 
  • #7
I somewhat forgot whether it's the negative or positive indicates spontaneity, you'll need to refer to your text to make sure.
 

What is a thermodynamically favored reaction?

A thermodynamically favored reaction is a chemical reaction that occurs spontaneously, meaning it releases energy and moves towards a more stable state.

What factors determine if a reaction is thermodynamically favored?

The factors that determine if a reaction is thermodynamically favored include the change in enthalpy (ΔH), change in entropy (ΔS), and temperature (T). A reaction is thermodynamically favored when ΔH is negative, ΔS is positive, and/or T is high.

How is thermodynamically favored different from kinetically favored?

Thermodynamically favored reactions are spontaneous and occur without any external influence, while kinetically favored reactions require an external energy source to occur at a reasonable rate. In other words, thermodynamically favored reactions are energetically favorable, while kinetically favored reactions are kinetically favorable.

Can a reaction be thermodynamically favored but not occur?

Yes, a reaction can be thermodynamically favored but not occur if the activation energy required to overcome the energy barrier is too high. In this case, the reaction will be kinetically hindered and may require a catalyst to occur at a reasonable rate.

How do chemists use thermodynamically favored reactions in practical applications?

Chemists use thermodynamically favored reactions in practical applications to produce desired products in a more efficient and cost-effective manner. They also use thermodynamic principles to predict the feasibility of reactions and design new reactions with higher yields and lower energy requirements.

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