Phases of Acetone and Diphenyl at room temp

In summary, the conversation discusses the physical properties of pure substances at 20°C, specifically the melting and boiling points of acetone and diphenyl. The speakers mention that while acetone has a melting point of -95°C and a boiling point of 56°C, it is still in liquid form at 20°C. They also discuss the misconception that just because something has not melted or boiled at a certain temperature, it must be solid. The correct understanding is that melting and boiling are transitions from solid to liquid and vice versa. The conversation concludes with the explanation that the acetone was already melted at -95°C and can be converted into vapor form by heating it past its boiling point.
  • #1
biochem850
51
0
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?
 
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  • #2
Acetone melts at -95 degrees. Room temperature is 20 degrees. Why would this be a solid?
 
  • #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.
 
  • #4
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
biochem850 said:
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.
 

1. What are the phases of acetone and diphenyl at room temperature?

The phases of acetone and diphenyl at room temperature are liquid and solid, respectively. Acetone is a volatile liquid that is commonly used as a solvent, while diphenyl is a solid compound that is often used in the production of plastics.

2. Why do acetone and diphenyl have different phases at room temperature?

The difference in phases between acetone and diphenyl at room temperature is due to their molecular structures. Acetone has a lower molecular weight and weaker intermolecular forces, allowing it to exist as a liquid at room temperature. Diphenyl, on the other hand, has a higher molecular weight and stronger intermolecular forces, causing it to be a solid at room temperature.

3. Can the phases of acetone and diphenyl change at different temperatures?

Yes, the phases of acetone and diphenyl can change at different temperatures. At lower temperatures, acetone can turn into a solid while diphenyl can become a liquid. This is because the strength of intermolecular forces increases with decreasing temperature, causing a change in the phase of the substances.

4. How do the phases of acetone and diphenyl affect their properties?

The different phases of acetone and diphenyl can affect their properties. For example, liquid acetone is more volatile and has a lower boiling point than solid diphenyl. The solid phase of diphenyl also tends to be more stable and have a higher melting point than liquid acetone.

5. Are there any other factors that can influence the phases of acetone and diphenyl?

Yes, factors such as pressure and the presence of other substances can also influence the phases of acetone and diphenyl. Changes in pressure can affect the strength of intermolecular forces, causing a change in the phase of a substance. The presence of other substances, such as solvents, can also impact the phase of a substance by affecting its intermolecular interactions.

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