[lonehavoc]

Hello all, I have a question about spontaneous and nonspontaneous reactions. I came across the idea that (at any temperature) as long as Enthalpy change is negative and Entropy change is positive the reaction will "always be spontaneous." I know that if Gibbs free energy is negative then the reaction is considered spontaneous, so what if the temperature is negative, wouldn't that make the statement false?

[Corribus]

Temperature is in Kelvin so by definition can't be negative.

[sjb]

Temperature is in Kelvin so by definition can't be negative.

For the purposes of this, this is probably acceptable but negative absolute temperatures are possible in theory.

[Meter]

Temperature is in Kelvin so by definition can't be negative.

For the purposes of this, this is probably acceptable but negative absolute temperatures are possible in theory.

I'd like to hear more about this. It was my impression that T < 0 K implied negative entropy?

[Borek]

I'd like to hear more about this. It was my impression that T < 0 K implied negative entropy?

https://en.wikipedia.org/wiki/Negative_temperature

The way I see it is that the problem stems from the way temperature is defined. We often define physical properties/quantities using terms we are accustomed to (that is: we observe at more or less STP). These definitions sometimes fail at extremes and produce nonsensical numbers. It typically means we should reconsider our understanding of the phenomena and refine the definition.

@lonehavoc - none of that applies to your question, for your needs Corribus' comment is spot on.

[Corribus]

Temperature is in Kelvin so by definition can't be negative.

For the purposes of this, this is probably acceptable but negative absolute temperatures are possible in theory.

Clearly outside thie scope of the question. You have to have an awareness of what level a student is at.