SRL Archive - Science

Hey guys, once again I am stuck on a question.

Without any further small talk, here it is.

For the process:

CH6(l) -> C6H6(s)

The standard entropy and enthalpy changes are:

*Delta*H = -9.83 KJ/mol and *Delta*S = -35.2 J K-1 Mol -1

Predict and explain the effect of an increase in the temperature on the spontaneity of the process

I am thinking that it makes it less spontanious, but I have no real reason why. Can anyone explain this to me?

When temperature is raised, the balance always goes to the endothermic side of the reaction (Le Chateliere). So, if the reaction is endothermic, it will become more spontaneous. If the reaction is exothermic, it will become less spontaneous.
*Delta*H = -9.83 KJ/mol (< 0, reaction is exothermic)
–> If you increase temperature, the reaction will become less spontanous

Not 100% sure, but I think it's like that…

http://en.wikipedia.org/wiki/Le_Ch%C3%A2telier%27s_principle

From: marpis
When temperature is raised, the balance always goes to the endothermic side of the reaction (Le Chateliere). So, if the reaction is endothermic, it will become more spontaneous. If the reaction is exothermic, it will become less spontaneous.
*Delta*H = -9.83 KJ/mol (< 0, reaction is exothermic)
–> If you increase temperature, the reaction will become less spontanous

Not 100% sure, but I think it's like that…

http://en.wikipedia.org/wiki/Le_Ch%C3%A2telier%27s_principle

Thats what I thought. But with entropy, the more ordered something is, the less spontaneous it is. When heat is added, the thing becomes more disordered, I think? So that would support the enthalpy part? :\

have you done gibbs free energy? delta G = delta H - T * delta S. when G is -, its spontaneous, G= 0, equilibrum and G +, non spontaneous.

so for your question. if you increase T it will make G more positive. G = negative - (more negative) which would equal a positive. so it would become more non spontaneous.

e: hopefully that made sense. my english skills have been lacking since im outta HighSchool
e2: didnt look at the date…silly me.