Isobaric Process: Finding Q, E, W.

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SUMMARY

The discussion focuses on calculating the change in internal energy (ΔIE), heat transfer (Q), and work (W) for an isobaric process involving 1.46 moles of an ideal gas heated from 431°C to 1227°C. The change in internal energy is calculated using the formula ΔIE = (3/2)nRT, resulting in 14.5 kJ. The work done during the isobaric process is expressed as W = P(Vf - Vi), but the challenge lies in determining the initial and final volumes. The hint provided emphasizes that only the product PΔV is necessary, and it can be related to the change in temperature (ΔT) using the ideal gas law.

PREREQUISITES
  • Understanding of the ideal gas law (PV = nRT)
  • Knowledge of thermodynamic processes, specifically isobaric processes
  • Familiarity with internal energy calculations for ideal gases
  • Basic algebra for manipulating equations involving pressure, volume, and temperature
NEXT STEPS
  • Explore the relationship between PΔV and ΔT using the ideal gas law
  • Study the derivation of work done in isobaric processes
  • Learn about the first law of thermodynamics and its application to ideal gases
  • Investigate how to calculate changes in volume for ideal gases under varying conditions
USEFUL FOR

This discussion is beneficial for students studying thermodynamics, particularly those focusing on ideal gas behavior and energy transfer in isobaric processes. It is also useful for educators and tutors looking to clarify concepts related to internal energy and work calculations.

yaylee
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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


change in IE = change in KE (because it is an ideal gas) = (3/2)nRT.
So, (3/2)(1.46)(8.314 x 10^-3)(1227-431) = 14.5 kJ (no issue here)

W = P(Vf-Vi), since it is an isobaric process.
However, how are you supposed to get the volumes of the initial and final state?

I tried pv = nRT, but am stuck with two unknowns. (Both Pressure, and Volume). Any suggestions? Many thanks in advance !
 
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Hint: You don't need separate values for P and V. You only need the combination PΔV.
Can you relate PΔV to ΔT using the ideal gas law?

Also, be careful with signs. You wrote ΔIE = Q + W. So, W is work done on the system. Does PΔV represent work done on the system or work done by the system?
 

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