TBR Chem- Carnot Engine Explanation. Help!!

[MetsFan96]

According to The Berkeley Review section on the Carnot Engine:

"1. A material that is normally a gas at room temperature and pressure is compressed into a liquid. Condensation is an exothermic process, so the material heats up and finishes as a liquid at higher temperature and pressure than it originally had."

The above description is for a counterclockwise path plotted on a Pressure v. Temperature graph. I don't understand how an exothermic process, in which the material would lose heat, would finish at a higher temperature. Any explanations would be greatly appreciated!

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[TraumaBlonde]

According to The Berkeley Review section on the Carnot Engine:

"1. A material that is normally a gas at room temperature and pressure is compressed into a liquid. Condensation is an exothermic process, so the material heats up and finishes as a liquid at higher temperature and pressure than it originally had."

The above description is for a counterclockwise path plotted on a Pressure v. Temperature graph. I don't understand how an exothermic process, in which the material would lose heat, would finish at a higher temperature. Any explanations would be greatly appreciated!

 

[TraumaBlonde]

 

[betterfuture]

The gas is condensing, meaning it changes its phase from gas to liquid. When it does this, the reaction releases heat - an exothermic reaction. The entropy of the surrounding increases always when there is an exothermic reaction. However, the system is more ordered. This results in a decrease in entropy of the system. In order for the reaction to occur, the entropy of the universe has to increase. That is why the reaction of gas to liquid occurs at a certain temperature, and thus reactions are temperature dependent as well. The bonds in a liquid phase are in a stable state and thus their energy lowers and energy is given off to the environment.

Temperature change is associated with heat. When you gain heat, it would make sense that the temperature increases. Though heat and temperature are similar they are not the same thing. Heat is the transfer of energy while temperature describes the average kinetic energy of something.

 

[bobeanie95]

Could you post a picture of the Temp v. Pressure graph?

 

[BerkReviewTeach]

According to The Berkeley Review section on the Carnot Engine:

"1. A material that is normally a gas at room temperature and pressure is compressed into a liquid. Condensation is an exothermic process, so the material heats up and finishes as a liquid at higher temperature and pressure than it originally had."

The above description is for a counterclockwise path plotted on a Pressure v. Temperature graph. I don't understand how an exothermic process, in which the material would lose heat, would finish at a higher temperature. Any explanations would be greatly appreciated!

betterfuture did a very good job here. When the gas is converted into a liquid, bonds (interactions between atoms) are formed, which releases heat energy into the environment. It just so happens that the liquid that is forming is the environment that absorbs that heat, making it a hot liquid. That hot liquid sits in coils on the back (and outside) of your refrigerator so that the hot liquid can give off that heat to the surroundings. The hot liquid formed upon compression is its own heat sink at first, before the heat is dissipated to the surroundings.

 

[betterfuture]

I try, but thank you! I was just learning this stuff and it just so happened that I saw this question and thought I would put my 2 cents.