1
$\begingroup$

I'm given that a solid is heated, beyond melting point and then the temperature of the liquid is 90 Celsius. When it cools, the temp falls to around 80 Celsius and stays constant for a period of minutes before falling again.

What would 80 Celsius represent here in thermodynamics terms?

Am I right in assuming it's the temperature just above the solid - liquid phase change on a cooling curve?

$\endgroup$
  • $\begingroup$ Have a look at this: bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/home_energy/… $\endgroup$ – Gert Feb 29 '16 at 16:06
  • $\begingroup$ Thanks, but in this question it mentions that the liquid remains at a constant temperature of 80 celcius for several minutes after falling from 90, and then falls again? $\endgroup$ – I come from a land down under Feb 29 '16 at 16:08
  • $\begingroup$ I suspect it might be the given liquid re solidifying? $\endgroup$ – I come from a land down under Feb 29 '16 at 16:09
  • $\begingroup$ So the "several minutes" must represent the phase change from liquid - solid right? $\endgroup$ – I come from a land down under Feb 29 '16 at 16:10
  • $\begingroup$ Yes, of course. As the link shows. Pure substances have a definite melting/solidifying point. During melting/solidifying the temperature remains constant, at least for slow cooling/heating. $\endgroup$ – Gert Feb 29 '16 at 16:11
1
$\begingroup$

Am I right in assuming it's the temperature just above the solid - liquid phase change on a cooling curve?

Not above, but exactly at the solid-to-liquid (or rather liquid-to-solid, also known as freezing or solidification) phase change region:

enter image description here

Considering water, it might start at $10 \;\mathrm{^\circ C}$ and is then cooled down to $-10 \;\mathrm{^\circ C}$. Along the way, there will be a while of constant-temperature cooling at exactly $0 \;\mathrm{^\circ C}$.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.