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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: birdnerd007 on October 18, 2019, 01:36:14 PM

Title: How much heat will be absorbed / released if a compound isothermally....cont.
Post by: birdnerd007 on October 18, 2019, 01:36:14 PM

Edit: I figure it out.
How much heat will be absorbed/released if a compound isothermally transforms from one phase to another? i.e. cristobalite to quartz.

I think the answer is non-zero but, I'm really not sure. Is this something that I should have on a chart? I have the specific heat capacities for both.

Title: Re: How much heat will be absorbed / released if a compound isothermally....cont.
Post by: Enthalpy on October 21, 2019, 02:57:10 PM

Hi birdnerd007, the heat capacities won't tell that. You need the heat of formation for both compounds, where "quartz" isn't as accurate as the considered allotrope.

The heat of transformation is small, so you need accurate heats of formation. I wouldn't be surprised if the heat of transformation was measured directly and is more accurate than both heats of formation.