# What is Isobaric process: Definition and 30 Discussions

In thermodynamics, an isobaric process is a type of thermodynamic process in which the pressure of the system stays constant: ΔP = 0. The heat transferred to the system does work, but also changes the internal energy (U) of the system. This article uses the physics sign convention for work, where positive work is work done by the system. Using this convention, by the first law of thermodynamics,

Q
=
Δ
U
+
W

{\displaystyle Q=\Delta U+W\,}
where W is work, U is internal energy, and Q is heat. Pressure-volume work by the closed system is defined as:

W
=

p

d
V

{\displaystyle W=\int \!p\,dV\,}
where Δ means change over the whole process, whereas d denotes a differential. Since pressure is constant, this means that

W
=
p
Δ
V

{\displaystyle W=p\Delta V\,}
.Applying the ideal gas law, this becomes

W
=
n

R

Δ
T

{\displaystyle W=n\,R\,\Delta T}
with R representing the gas constant, and n representing the amount of substance, which is assumed to remain constant (e.g., there is no phase transition during a chemical reaction). According to the equipartition theorem, the change in internal energy is related to the temperature of the system by

Δ
U
=
n

c

V
,
m

Δ
T

{\displaystyle \Delta U=n\,c_{V,m}\,\Delta T}
,where cV, m is molar heat capacity at a constant volume.
Substituting the last two equations into the first equation produces:

Q

=
n

c

V
,
m

Δ
T
+
n

R

Δ
T

Q

=
n
Δ
T
(

c

V
,
m

+
R
)

Q

=
n
Δ
T

c

P
,
m

{\displaystyle {\begin{aligned}Q&=n\,c_{V,m}\,\Delta T+n\,R\,\Delta T\\Q&=n\Delta T(c_{V,m}+R)\\Q&=n\Delta Tc_{P,m}\end{aligned}}}
where cP is molar heat capacity at a constant pressure.

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1. ### Change in the energy content of an isobaric process

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2. ### T and V changing in an isobaric process

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3. ### B Adiabatic or Isobaric process?

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4. ### Thermodynamic Process: Is Work Conserved?

What is wrong with this logic, if any? It does not seem like this should be true but maybe I'm mistaken. Assuming the process consists of two isobaric processes and two isothermal processes the work from B to C in terms of p1, p2, V1, and V2 is given by the following. 1) WBC=p2(VC-VB) 2)...
5. ### Isobaric and Isochoric Process Combined

Homework Statement [/B] This is a very basic question. I have a cylinder filled with air having stops at a particular height . First part of the process is isobaric as piston is free to move and P is constant. When piston reaches stops this becomes isochoric process as volume is constant. So...
6. ### Change in the internal energy of an isobaric process

Homework Statement A cylinder contains 0.250mol of carbon dioxide (CO2) gas at a temperature of 27.0∘C. The cylinder is provided with a frictionless piston, which maintains a constant pressure of 1.00atm on the gas. The gas is heated until its temperature increases to 127.0∘C. Assume that the...
7. ### Ideal gas through Isobaric process

Homework Statement This is probably a real easy task for most, but I simply CANNOT manage to calculate it, even given the correct answer. I will translate it as best I can and hope I don't phrase it in a way that causes misunderstandings: 12 Moles of an ideal gas go through an Isobaric...
8. ### What is the Internal Energy of 158 moles of CO2

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9. ### The internal energy in isobaric process

1. Homework Statement When volume changes from V to 2V at constant pressure then the change in internal enrgy will be? 2. Homework Equations ΔU= nCvΔT 3. The Attempt at a Solution I have used the equation ΔU= nCvΔT but the answer is PV/γ-1
10. ### Isobaric process for a Van der Waals gas

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11. ### How is isobaric process physically possible?

We have an ideal gas enclosed in cylinder whose top is covered by a piston of certain weight ##mg##. At this stage, the piston is at rest which means the force by which the gas acts on the piston (##F=PA## where ## P## is the gas pressure and ##A## is the cross sectional area of the cylinder) is...
12. ### Archived Finding the thermal energy and Q for an isobaric process.

Homework Statement How much work is done on the gas in the process shown in figure P12.24. This is from College Physics: A strategic approach, 2nd addition, by Knight, et al. Ch.12, #24 The graph shown is kPa vs V(cm^3). It's a constant temperature process (isobaric) at 200 kpa. I was able to...
13. ### Change in Internal Energy of an Isobaric Process

In an isobaric process of 1 mole of a monatomic ideal gas, the pressure stays the same while the volume and temperature change. Let's take an isobaric expansion where the volume increases by 2m3 and the pressure stays at 5kPa. If the work done by the gas is the pressure times the change in...
14. ### Isobaric Process, finding Change in Internal Energy

Homework Statement Assume nitrogen gas (N2) is an ideal gas. n = 7.57 moles of N2 gas are heated isobarically (at constant pressure) from temperature To = 18.6 oC to temperature Tf = 50.9 oC. Find: c) ΔIE, the change in internal energy of the N2 gas Homework Equations Change in IE...
15. ### Isobaric Process: Finding Q, E, W.

Homework Statement n = 1.46 moles of ideal gas are heated isobarically (at constant pressure) from temperature To = 431 oC to temperature Tf = 1227 oC. Find: change in Energy, Q, W. Homework Equations Change in IE = Q + W W (isobaric process) = P(vf-v1) The Attempt at a Solution...
16. ### Heat capaticy of isobaric process with real gas

Hey, during last lecture of thermodynamics we did polytropic processes, and with no discuss teacher said, that isobaric process is in general polytropic. If we had ideal gas, then it is clear, bud what if the gas isn't ideal? I tried to proof it, but I stuck and don't know how to continue...
17. ### Isobaric process. Find magnitude of heat transfer

Hi there, I'm having a great deal of trouble with this thermodynamics question. Cylinder filled with steam at 350 kN/m2. Initial volume is 0.05 m3. Sufficient heat transfer is effected to raise the internal energy in each cylinder by 50 kJ. The piston is moved slowly to maintain the...
18. ### Isobaric process experiment with plastic tube and hot water

Hi! I have this experiment, that keeps getting me frustrated. The experiment is simple: We have hot water and a long plastic tube with one end closed. We simply measure how much water is in the tube and from that we get the water volume (water is in cylinder shape). But there is something I...
19. ### Interpreting Diagrams: Why is C_v Used in Isobaric Process?

Hello All, I am interpreting a diagram from the following question. (I didnt have a chance to take thermo and I learned it by myself so I might have some problems) http://www.physicsgrad.com/pgre/9677-15 I understand that I can just do ΔW and I get the right answer, but upon doing it...
20. ### Method to carry out the isobaric process

hi ... These days i am trying to make sense of the various processes of thermodynamics and so far i have tried the isothermal process , and isochoric process (which is quite simple i think). Now i am trying to describe what i have understood by the isobaric process: According to the basic...
21. ### Isobaric process; change in internal energy

I know this question has been done to death and I have had a look through past questions on this forum and others but I can't find anything that is helpful to this particular question! Homework Statement An ideal monatomic gas expands reversibly at a fixed pressure of 10^5 Pa from a...
22. ### Thermodynamics: Isobaric process finding volume of steam.

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23. ### Thermodynamics problem- isobaric process

Homework Statement One mole of an ideal monatomic gas is taken through the cycle ABCA shown schematically in the diagram. State A has volume 0.0208 m3 and pressure 1.22 × 10 5 Pa, and state C has volume 0.0524 m3 Process CA lies along the 305 ±1 K isotherm. The molar heat capacities for...
24. ### Isobaric Process finding G using (deltaG-deltaGo)

Can anyone help me with understanding what is going on at page 11 of these notes? http://www.chem.utoronto.ca/coursenotes/CHM223/Section%205B%20Fall%202010.pdf Do you get why there is 2 delta Gs? I am really confused with what he was trying to do there? ΔG(37oC) – ΔG(25oC) ≈ – (T – 298)...
25. ### Isobaric Process: Fill in ΔP for Homework Equation

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26. ### Solving Isobaric Process Heat Addition Problem

NVM I solved it. Thanks for reading anyway :) Homework Statement 610 J of heat is added to 3.4 mol of a monatomic ideal gas at constant pressure. Find the change of temperature of the gas.Homework Equations At isobaric conditions, w = p\DeltaV = nR\DeltaT w = nR\DeltaTThe Attempt at a...
27. ### What is the work done by an ideal gas in an isobaric process?

[SOLVED] Isobaric process Hi, need some help with this. I got to moles of an ideal gas that are heated at constant pressure from T=27 C to T=107C. How do I calculate the work done by the gas? I know that for a isobaric process the work is given by W = p(V2-V1) Thanks
28. ### Isobaric Process: del(H) = mC(v)dT + (P.dV)/J

Homework Statement Consider 1 gram of an ideal gas undergoing isobaric process. Suppose del(H) be the amount of heat given to it. Then, del(H) = dU + del(W) del(H) = 1 x C(v)dT + (P.dV)/J...
29. ### Going Crazy: Solving an Isobaric Process Problem

This problem is going to make me go crazy... 4. In the figure below, an ideal gas is slowly compressed at a constant pressure of 2.0 atm from 10.0 L to 2.0 L. This process is represented as the path B to D. In this process, some heat flows out and the temperature drops. If the heat lost from...
30. ### Change in internal energy for an isobaric process?

Question: When a quantity of monatomic ideal gas expands at a constant pressure of 4.00 \times 10^{4} {\rm Pa}, the volume of the gas increases from 2.00 \times 10^{ - 3} {\rm m}^{3} to 8.00 \times 10^{ - 3} {\rm m}^{3}. A. What is the change in the internal energy of the gas? It's isobaric...