What is the change in entropy of the gas?

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Homework Help Overview

The discussion revolves around the change in entropy of one mole of an ideal gas undergoing an isothermal expansion from an initial volume of 1x10^3 cm3 to a final volume of 2x10^3 cm3. The gas is in contact with a heat reservoir, maintaining a constant temperature throughout the process.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the formula for entropy change in isothermal processes, with some referencing the relationship between heat capacity and volume. Others highlight the significance of internal energy in the context of isothermal conditions.

Discussion Status

There are various approaches being explored regarding the calculation of entropy change. Some participants have provided equations and relationships relevant to the problem, while others are questioning the implications of internal energy in an isothermal process.

Contextual Notes

Participants note that the problem involves an ideal gas and is constrained by the conditions of isothermal expansion, which affects the internal energy considerations.

daisyi
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One mole of an ideal gas in a cylinder fitted with a piston is made to expand slowly (reversible) from an initial volume of 1x10^3 cm3 to a final volume of 2x10^3 cm3. The cylinder is in contact with a heat reservoir so that, throughout the expansion process, the gas is held at a constant temperature. What is the change in entropy of the gas?
 
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isothermal process

For an isothermal process, [itex]\Delta S = Q/T[/itex].
 
This problem can be solved using

[tex]\Delta S = nC_Pln\frac{V_2}{V_1}+nC_Vln\frac{P_2}{P_1}[/tex]

All you need to do now, is to recall the relationship between an ideal gas and the heat capacity. You don't need the temperature to solve this problem.
 
Along with Doc's equation, you'll want to use [itex]\Delta U = Q + W[/tex][/itex]
 
but for isothermal process change in internal energy(delta U) is equal to 0.
 

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