Thermodynamics Homework: Find Work Given Heat & Temp Change

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Homework Help Overview

The discussion revolves around a thermodynamics problem involving an ideal monatomic gas, where heat is added and a temperature change occurs. Participants are tasked with finding the work done by the gas during this process, given specific heat and temperature values.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the relationship between internal energy change and temperature change, questioning how to relate these concepts. There are attempts to apply the first law of thermodynamics, but confusion arises regarding the correct application of formulas and the relationship between temperature in Kelvin and energy in Joules.

Discussion Status

Some participants have offered guidance on checking reference materials for equations related to internal energy and the specific properties of monatomic gases. There is an ongoing exploration of how to correctly apply the first law of thermodynamics and the equipartition of energy principle, but no consensus has been reached on the correct approach yet.

Contextual Notes

Participants are working under the constraints of the problem statement and the need to apply thermodynamic principles correctly. There is an acknowledgment of confusion regarding the relationships between heat, work, and temperature changes in the context of ideal gases.

Robershky
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Homework Statement



When 1380 J of heat are added to one mole of an ideal monatomic gas, its temperature increases from 272 K to 275 K. Find the work done by the gas during this process.

Homework Equations



I assume [tex]\Delta[/tex]U = Q - W is the formula to use. But for some reason I'm just confused.

The Attempt at a Solution



I tried using 1380 = 275 - W, and got -1105. But that is not the correct answer.
 
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Can you relate [itex]\Delta U[/itex] to [itex]\Delta T[/itex]?
 
That's the problem, I don't understand how they relate. Is there a conversion from Kelvin to Joules? Or do I just use 3K = 1380J - W?
 
Check your book, notes, or reference for an equation of the internal energy (U) of an ideal gas.
 
Internal energy increases with increasing temperature, but the exact relation will depend on the type of gas. You should figure out how many degrees of freedom are present in a monatomic gas, then use equipartition of energy to express the internal energy as a function of temperature.
 
Robershky said:

Homework Statement



When 1380 J of heat are added to one mole of an ideal monatomic gas, its temperature increases from 272 K to 275 K. Find the work done by the gas during this process.

Homework Equations



I assume [tex]\Delta[/tex]U = Q - W is the formula to use. But for some reason I'm just confused.

The Attempt at a Solution



I tried using 1380 = 275 - W, and got -1105. But that is not the correct answer.
You are given Q and you can determine [itex]\Delta U = nC_v\Delta T[/itex]. So it is just a matter of applying the first law to determine W.

AM
 

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