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Phases of Acetone and Diphenyl at room temp

  1. Sep 16, 2012 #1
    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?
     
  2. jcsd
  3. Sep 16, 2012 #2
    Acetone melts at -95 degrees. Room temperature is 20 degrees. Why would this be a solid?
     
  4. Sep 16, 2012 #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.
     
  5. Sep 16, 2012 #4

    AGNuke

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    Gold Member

    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.
     
  6. Sep 16, 2012 #5
    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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