Cooling bath temperature question

  • Thread starter kottur
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Homework Statement



A cooling bath is prepared in a laboratory by mixing chunks of solid CO2 with ethanol. CO2(s) sublimes at -78.5°C to CO2(g). Ethanol freezes at -114.5°C and boils at +78.4°C. State the temperature of this cooling bath and describe what will be seen when it is prepared under ordinary laboratory conditions.

The answer is -78.5°C.

Homework Equations



Not sure if there are any equations. Might just be a graph with a critical point or something like that.

The Attempt at a Solution



First of all, the definition of a cooling bath is a bath that maintains a low temperature close to 0°C right? I suppose that the mixture of CO2 and ethanol is with solid CO2 (given) and liquid ethanol, so does the ethanol break up the CO2 or something? Anyway at -78.5°C ethanol is still liquid and CO2 is just in between solid and gaseous state. I don't understand how the answer is -78.5°C and I also would like to understand what happens in the cooling bath like the question states.

Thank you! :)
 

Answers and Replies

  • #2
Borek
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It is mostly about the latent heat - question assumes there is enough solid carbon dioxide used.

Mixture is prepared using ethanol at - most likely - room temperature, so it will be cooled down by subliming CO2. How far down can the temperature go?
 

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