Change in the internal energy of an isobaric process

In summary, the conversation discusses finding the change in internal energy (ΔU) of a cylinder containing 0.250 mol of CO2 gas as it is heated from 27.0∘C to 127.0∘C with a constant pressure of 1.00 atm. The ideal gas law is used to calculate ΔU, but the incorrect value of Cv was initially used, leading to an incorrect answer. After finding the correct value of Cv in moles, the correct answer for ΔU is obtained.
  • #1
Stendhal
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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 CO2 may be treated as an ideal gas.

Homework Equations


ΔU = ΔQ -W

ΔU = C_v*n*ΔT

The Attempt at a Solution


In this case, I thought that ΔU could be set equal to (5/2)nRΔT since we know all of those variables. The value I got for that was ΔU = 520J, but that isn't the correct answer. Any help in explaining where I am going wrong would be appreciated greatly!
 
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  • #2
Did you look up the value of Cv on line or in the literature?
 
  • #3
Whoops, to answer that, I did. The value I looked up however was not in units of moles, so I got the wrong answer. Found a value of Cv in moles and got the right answer.
 
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Related to Change in the internal energy of an isobaric process

1. What is an isobaric process?

An isobaric process is a thermodynamic process in which the pressure of a system remains constant while other variables, such as volume and temperature, may change.

2. How does the internal energy change in an isobaric process?

In an isobaric process, the internal energy changes due to the exchange of heat between the system and its surroundings. If the process is reversible, the change in internal energy can be calculated using the formula ΔU = nCpΔT, where n is the number of moles, Cp is the molar heat capacity at constant pressure, and ΔT is the change in temperature.

3. What factors affect the change in internal energy in an isobaric process?

The change in internal energy in an isobaric process is affected by the amount of heat exchanged, the number of moles of the substance, and the molar heat capacity at constant pressure.

4. What is the significance of an isobaric process in thermodynamics?

Isobaric processes are important in thermodynamics because they allow us to study the relationship between pressure, volume, and temperature of a system while keeping one variable constant. This helps us understand how a system responds to changes in its environment and how energy is transferred.

5. Can the internal energy of a system remain constant during an isobaric process?

No, the internal energy of a system cannot remain constant during an isobaric process. This is because heat is constantly being exchanged with the surroundings, causing a change in the internal energy of the system.

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