Liquid to gas expansion temperature change in a tank

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Discussion Overview

The discussion revolves around the calculation of temperature changes during the phase transition of a liquid to gas in a tank, specifically under conditions of constant pressure and adiabatic processes. Participants explore the implications of these conditions on the final temperature of the system.

Discussion Character

  • Technical explanation
  • Homework-related
  • Conceptual clarification

Main Points Raised

  • One participant describes a scenario involving a tank with an initial volume and pressure, where the liquid boils to maintain pressure, leading to a final volume and a drop in temperature, and seeks a formula to calculate the final temperature.
  • Another participant references Charles's law, suggesting that pressure is inversely proportional to temperature, and prompts consideration of whether the substance in question is volatile.
  • A third participant reiterates the initial scenario and asks for a specific problem to focus on, while mentioning the first law of thermodynamics and the relationship between internal energy and the enthalpy of vapor exiting the tank.
  • A later reply acknowledges a mistake made in the discussion, indicating a desire to avoid repetition of the error.

Areas of Agreement / Disagreement

The discussion contains multiple viewpoints and does not reach a consensus on the appropriate approach or formula for calculating the final temperature after the phase change.

Contextual Notes

Participants have not fully defined the assumptions regarding the properties of the liquid or the specifics of the phase change process, which may affect the calculations and conclusions drawn.

PHstud
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Hello !

I have troube doing a calculation.

Let's say we have a volume Vi in a tank at a pressure Pi. If I let my tank open, the tank's liquid will start to boil to keep the pressure Pi inside the tank. Now, at the end, I will have a volume Vf in the tank, and still a pressure Pi.
But the temperature of the tank will have dropped (lets consider adiabatic), which formula could I use to find the final Temperature ? (Maybe using energy of phase change?)

Thank you !
 
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Think logically man,remember Charlie's law stating pressure inversely proportional to temperature.
Please examine whether the substance is volatile or not
 
PHstud said:
Hello !

I have troube doing a calculation.

Let's say we have a volume Vi in a tank at a pressure Pi. If I let my tank open, the tank's liquid will start to boil to keep the pressure Pi inside the tank. Now, at the end, I will have a volume Vf in the tank, and still a pressure Pi.
But the temperature of the tank will have dropped (lets consider adiabatic), which formula could I use to find the final Temperature ? (Maybe using energy of phase change?)

Thank you !
Is this a homework problem?

Do you have a specific problem that you can focus on? The basic relationship, derived from the open system version of the first law of thermodynamics, is that the rate of change of total internal energy within the tank is equal to mass rate of vapor exiting times the enthalpy of the exiting vapor.
 
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Likes   Reactions: John Dalton
Apologies my man.I have made a mistake.won't do this again.
 

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