Any source that explains Heat-Work for Thermodynamics

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I'm actually having the worst time understanding this whole concept

Cornot Cycle
Heat Engines
Refridgeration

The whole adiabatic, isothermic, isochoric, isobaric thing

Closed, Open, Isolated systems

Is there any source that actually explains it rather clearly. I read TBR and saw some youtube videos, didn't do much

All I got out of it was W = P/\V and q is heat, but when I do questions I can't seem to get anything correct

Is there any source that explains it clearly/can help this idiot understand it because I've spent a few hours and it's been to no avail

 

[PocketJacks]

Check out Freelanceteacher's channel on youtube

 

[gumdrops]

I'm actually having the worst time understanding this whole concept

Cornot Cycle
Heat Engines
Refridgeration

The whole adiabatic, isothermic, isochoric, isobaric thing

Closed, Open, Isolated systems

Is there any source that actually explains it rather clearly. I read TBR and saw some youtube videos, didn't do much

All I got out of it was W = P/\V and q is heat, but when I do questions I can't seem to get anything correct

Is there any source that explains it clearly/can help this idiot understand it because I've spent a few hours and it's been to no avail

You're not an idiot. This stuff is some of the hardest stuff to understand on the MCAT, conceptually. I'd actually recommend you do more and more problems. I used to read explanation after explanation to no avail.

Let me see if I can help with this. Think of a gas as doing work when it is expanding. If a gas is doing work, energy is leaving the system just the way it does when we do "work." If pressure stays the same and volume expands, that's a positive change in work and thus it would just be W = -P(deltaV). So change in U would be equal to heat - work done by gas.

If a gas is being compressed by an outside force such as a piston, work is being done on the gas. Since the volume would be decreasing, the change in work would be positive or W = P(delta V). So the total energy of the gas would increase. delta U = heat + work done on the gas.

For heat, heat entering the system would obviously be positive and heat leaving the system would be negative. Try to find problems where you'd have to calculate these changes if the system were adiabatic (heat does not leave or enter the system so heat becomes a nonfactor) or isobaric (pressure stays the same) to see whether you understand just this concept. Then obviously work up to trickier problems where the pressure changes. Please let me know if any of this is wrong. Good luck!

 

[balla121]

thermo was one of the hardest classes ive ever taken... i suggest a chemistry textbook to get a better conceptual understanding of the material. as for the cycles that you have listed, you shouldmhave the realization that the amount of heat or energy to change phases >>>amount of heat or energy from a change in temperature due to specific heat of the material. This is the basic concept to cycles.

a good example of a cycle would be an air conditioner... it sucks up heat energy inside the room and releases it outside the room, thus the temperature inside is cooled. This process can occur because the solution used in the air conditioner can evaporate using heat energy in the air. The newly made gas can then be transported to the back of the airconditioner on the side facing the outside of the room and proceed to condense and thus releasing the energy to the outside and producing the liquid form again. this process occurs over and over making a cycle.

other cycles are just variations of this concept. heat engines on the other hand, instead of changing heat to heat, it changes heat to work...

its tough material but the amount of knowledge you need for the mcat is minimal. good luck 🙂

 

[fugacitybrah]

This might be a little over kill but if you really want to understand the thermodynamics (and there may be some calculus in there) try to get a hold of Thermodynamics: An Engineering Approach by Cengel and Boles. This book saved my ass when I was taking thermo. Helps give you a conceptual understanding. Again, it might be overkill --check it out only if you have the time.

 

[swim88]

I'm actually having the worst time understanding this whole concept

Cornot Cycle
Heat Engines
Refridgeration

The whole adiabatic, isothermic, isochoric, isobaric thing

Closed, Open, Isolated systems

Is there any source that actually explains it rather clearly. I read TBR and saw some youtube videos, didn't do much

All I got out of it was W = P/\V and q is heat, but when I do questions I can't seem to get anything correct

Is there any source that explains it clearly/can help this idiot understand it because I've spent a few hours and it's been to no avail

Check out the videos on aklectures.com
He takes a somewhat simple approach but it helped me gain a basic understanding.