Thermodynamics question >_<

In summary: A cylinder contains 2 moles of an ideal monatomic gas that is initially at state A with a volume of 1.0 x 10^-2 m3 and a pressure of 4.0 x 10^5 Pa. The gas is brought isobarically to state B. where the volume is 2.0 x 10^-2 m3. The gas is then brought at constant volume to state C, where its temperature is the same as at state A. The gas is then brought isothermally back to state A.In summary, the pressure at state C is 4.0 x 10^5 Pa.
  • #1
Div
2
0

Homework Statement


A cylinder contains 2 moles of an ideal monatomic gas that is initially at state A with a volume of 1.0 x 10^-2 m3 and a pressure of 4.0 x 10^5 Pa. The gas is brought isobarically to state B. where the volume is 2.0 x 10^-2 m3. The gas is then brought at constant volume to state C, where its temperature is the same as at state A. The gas is then brought isothermally back to state A.
a. Determine the pressure of the gas at state C.
b. State whether this device is a refrigerator or a heat engine. Justify your answer.

So here's my version of that,


n = 2mol
stateA
v = 1.0 x 10-2m3
p = 4.0 x 105 Pa
stateB
v = 2.0 x 10-2 m3
p = 4.0 x 105 Pa (Isobaric Process)
stateC
v = 2.0 x 10-2 m3 (Isochoric Process)
tc = ta
w = 0 (isochoric)
p = ?

Homework Equations


p=F/A?
w=pdeltav?

The Attempt at a Solution


a)i know that the fact tc = ta has something to do with this, but when i consider this i would get deltau to = 0 due to the isothermal process right? and if deltau = 0 then q=w then t=p.02? but then how would i solve for p if i don't know t? >_< this is confusing...
b)i know that if i made a pv graph for this id have something like A---->B then C directly under B but because i don't know the answer to question a i don't know exactly where, also does that even have anything to do with it? I am guessing that with less volume you have higher temperature and the opposite with lots of volume but then my teacher showed us that in carnot cycles its actually colder when there's less volume! i would have to say refrigerator just because at b; the only state where temperature changes it would increase becauseto maintain the same pressure at an increased volume you would have to have a higher temperature right?
 
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  • #2
help please? :(
 
  • #3
Div said:

The Attempt at a Solution


a)i know that the fact tc = ta has something to do with this, but when i consider this i would get deltau to = 0 due to the isothermal process right? and if deltau = 0 then q=w then t=p.02? but then how would i solve for p if i don't know t? >_< this is confusing...
b)i know that if i made a pv graph for this id have something like A---->B then C directly under B but because i don't know the answer to question a i don't know exactly where, also does that even have anything to do with it? I am guessing that with less volume you have higher temperature and the opposite with lots of volume but then my teacher showed us that in carnot cycles its actually colder when there's less volume! i would have to say refrigerator just because at b; the only state where temperature changes it would increase becauseto maintain the same pressure at an increased volume you would have to have a higher temperature right?
Use the ideal gas law and do a PV diagram.

The path from A to B is a horizontal line to the right a distance of V0 (1.0 x 10^-2 m^3) . What happens to T from A to B? (use Ideal Gas Law). Is heat flowing? What direction (into or out of the gas?).

The path from B to C is a vertical line. What is the pressure at C? (use Ideal Gas Law). Is heat flowing? Direction?

For the path from C to A, T is constant so how does P vary with V? (use Ideal Gas Law). Is CA a straight line? Curve? Is heat flowing? Direction?

What does the area between inside the path represent? Is it positive or negative? (you have to add the areas under each path - careful with signs). Is work being done by the gas or is work being on the gas?

AM
 

1. What is thermodynamics?

Thermodynamics is a branch of physical science that deals with the relationships between heat, energy, and work.

2. What are the laws of thermodynamics?

The laws of thermodynamics are fundamental principles that govern the behavior of energy in physical systems. They include the laws of conservation of energy, entropy, and entropy production.

3. What is the difference between heat and temperature in thermodynamics?

Heat is a form of energy that is transferred from one object to another due to a difference in temperature. Temperature is a measure of the average kinetic energy of the particles in a substance.

4. How does thermodynamics apply to everyday life?

Thermodynamics has many practical applications in everyday life, such as in cooking, refrigeration, and energy production. It also helps us understand the behavior of gases, liquids, and solids.

5. What are some common misconceptions about thermodynamics?

Some common misconceptions about thermodynamics include the idea that energy can be created or destroyed (when in fact it can only be converted), and that all processes must occur in the direction of increasing disorder (when in reality this only applies to isolated systems).

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