Is Oxyhydrogen a spontaneous reaction at very high temperatures?

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Discussion Overview

The discussion centers around the spontaneity of the reaction between hydrogen and oxygen gases at very high temperatures, particularly in the context of thermodynamic principles. Participants explore the implications of enthalpy and entropy changes on the spontaneity of reactions, including comparisons to other reactions such as the burning of magnesium.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant asserts that the reaction between hydrogen and oxygen is non-spontaneous at high temperatures due to the relationship \DeltaH - T\DeltaS < 0, suggesting that a sufficiently high temperature could lead to a positive value that indicates non-spontaneity.
  • Another participant agrees with this assertion and cites the efficiency of high-temperature electrolysis of water as a relevant example.
  • A later participant questions whether the same reasoning applies to the burning of magnesium, noting that while it is exothermic, it also has a negative change in entropy, suggesting that high temperatures could affect its spontaneity as well.
  • One participant confirms the correctness of the question regarding magnesium, indicating agreement with the concern raised.

Areas of Agreement / Disagreement

Participants generally agree on the application of thermodynamic principles to the reaction between hydrogen and oxygen, but there is a discussion about whether the same principles apply to the burning of magnesium, indicating some uncertainty and potential disagreement.

Contextual Notes

The discussion does not resolve the implications of entropy changes in various reactions, nor does it clarify the specific conditions under which these reactions may or may not be spontaneous.

ineedaquickie
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Hi, this may seem like a noob question for you geeks out there, but I can't wrap my head around this.
The formula for a spontaneous reaction is \DeltaH-T\DeltaS < 0
Basically, since the reaction between hydrogen and oxygen gas has a negative change in enthalpy it must mean that if the temperature in Kelvin is big enough then the reaction between oxygen and hydrogen gas will not be spontaneous.

Because the negative T multiplied with the negative change in entropy will be more positive than the enthalpy change and it won't be a spontaneous process? right?
 
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I'm sorry to bring this up, but does the same count for the burning of magnesium. Burning of magnesium is exothermic, but the change in entropy is negative as well so if the temp is big enough, the reaction won't be spontaneous. Correct?
 

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