Phases of Acetone and Diphenyl at room temp

  • Thread starter biochem850
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  • #1
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I was reviewing a chart of Physical properties of pure substances (20 °C)

Acetone has a melting point of -95°C and boiling point of 56°C so you'd assume it's solid (but obvioulsy it's liquid). In addition, Diphenyl has a melting point of 70°C and boiling point of 255°C so you'd assume it's liquid (but it's solid).

What characteristics am I overlooking?
 

Answers and Replies

  • #2
901
3
Acetone melts at -95 degrees. Room temperature is 20 degrees. Why would this be a solid?
 
  • #3
51
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20°C is is greater than -95°C (melting ) so acetone would not have melted and is less than 56°C (boiling) so acetone would not have evaporated; I'm assuming the normal phase of acetone is liquid and you don't merely assume because something hasn't melted or boiled that it is solid? Is my presumption correct?

I honestly don't see what I'm missing.
 
  • #4
AGNuke
Gold Member
455
9
20°C is more than -95°C, so the acetone will melt. See, water has melting point of 0°C, but you "drink" water, don't you? According to your argument, we must be eating ice.

Acetone was melted long ago (-95°C is not the temperature to come across easily), so we see it in its melted, liquid form. Just heat it past its boiling point, it will convert into vapour form.
 
  • #5
901
3
20°C is is greater than -95°C (melting ) so acetone would not have melted and is less than 56°C (boiling) so acetone would not have evaporated; I'm assuming the normal phase of acetone is liquid and you don't merely assume because something hasn't melted or boiled that it is solid? Is my presumption correct?

I honestly don't see what I'm missing.

melting is the transition from solid to liquid.

-95 is when solid acetone transforms to liquid acetone. you then raise the temperature to 20 degrees, which is below 56.
 

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