Thermodynamical State: Questions & Answers

  • Thread starter Thread starter Ahsan Khan
  • Start date Start date
  • Tags Tags
    State
Click For Summary
SUMMARY

The discussion centers on the concept of thermodynamic states and state functions, specifically addressing whether a system at a particular state has unique values for state functions such as temperature, pressure, and internal energy. It is established that while state functions provide a complete description of a system, two similar systems at the same state can have different internal energies. Additionally, it is clarified that thermodynamic processes can occur where the initial and final states differ, even if the change in internal energy is zero. The conversation emphasizes that knowing internal energy alone does not predict other state functions' values.

PREREQUISITES
  • Understanding of thermodynamic state functions (temperature, pressure, volume, internal energy)
  • Familiarity with thermodynamic processes (adiabatic, isobaric, isothermal, isochoric)
  • Basic knowledge of ideal gas laws and equations of state
  • Concept of internal energy and its relationship to state variables
NEXT STEPS
  • Study the relationship between state functions and thermodynamic processes in detail
  • Learn about the implications of the first law of thermodynamics on internal energy
  • Explore the concept of phase transitions and their effect on state functions
  • Investigate real gas behavior and deviations from ideal gas laws
USEFUL FOR

Students of thermodynamics, educators teaching thermodynamic principles, and professionals in engineering or physical sciences seeking to deepen their understanding of thermodynamic states and processes.

Ahsan Khan
Messages
270
Reaction score
5
Hi All,
During my study of thermodynamics these days I have a little confusion regarding the concept of state of a system and state functions. Here I begin what confuses me.
We know temperature, pressure, volume, internal energy, entropy etc. are state functions. 1.I am wondering if a system at a particular state has some unique values of state functions?
2. What does it really mean by a state of a thermodynamic system?
3.Can two simillar systems at same state have different internal energy? OR Do internal energy is some special type of state function, which could indepedently clearifies what is the state of the system.
4. Is it possible for any process ,(to occur) where the initial and final state are different though the change internal energy is zero.
In short the concept of state confuses me. Any help will be highily appreciated.
REGARDS!
 
Science news on Phys.org
1. I am wondering if a system at a particular state has some unique values of state functions?
That's sort-of correct.
The physical "state" of a system is the condition it is in.
Like when you come in muddy and someone says "Look at the state you are in!" Your state is your physical condition.

We represent a thermodynamic state mathematically as a set of numbers - when we have enough numbers that, from them, we can determine everything we need to know about the system, then we have a complete description of it's state. We will often refer to the set of numbers as the state as a kind of shorthand.

2. What does it really mean by a state of a thermodynamic system?
Classically, the state of an ideal gas is completely described by it's volume, pressure, and temperature (and the number of molecules).

3. Can two simillar systems at same state have different internal energy? OR Do internal energy is some special type of state function, which could indepedently clearifies what is the state of the system.
You should be able to figure this out from the previous - you know how to find the internal energy of a system from it's state variables: does that relationship allow more than one value for a given state?

4. Is it possible for any process (to occur), where the initial and final state are different though the change internal energy is zero.
Of course - but you know this one too: the thermodynamic processes are adiabatic, isobaric, isothermal and isochoric. You have the internal energy relations for each one - which is/are zero?
 
Thanks you so much Simon Bridge, I really got benifitted by your answers. Here one more thing I want to get clearified...
 
Suppose i have two containers of raw rice of same hybrid (i.e having same internal energy) and i started cooking them using same ingridents but by different mode of heating. If after being cooked to the same level it is found that the change in internal energy in both is the same, now is it necessary that they would be of same taste and having same final temperature? thanks!
 
Taste is not a thermodynamic property.

Cooking is not exact, and neither is taste.
As a result, it is quite easy to make two bowls of rice taste sufficiently the same that many independent diners will agree "they taste the same!"

We don't usually have or need a complete description of the state of something to be able to do useful things with it.
 
Ok.., means by just knowing the internal energy of a paeticular well known sysrem, one can not pridict other state functions(their values), the system is in. Can this be finally assumed?
Or i can say two systems undegoes same change in internal energy from same initial state may have diffetent final temperature. WITH REGARDS!
 
Last edited:
I will further be very thankfull to anybody who could tell me that, if two systems(similar) are at same state, will that mean that all the state functions will have the same value or not? I really very curious to understant. I am sorry for my dull mind:)
 
Sure - the configuration of a system, even something like an ideal gas, can lead to different states with the same internal energy.

One of the things worth studying as you progress through life is how little information you need before you know everything about the system ... and how little you need to know to do something useful with it.

And an inquiring mind is seldom dull - at least not for long.
 
Thanks I understood the matter now.Love to have more discussions in future. Thanks again:)
 

Similar threads

Undergrad Identification of changes in internal energy with work (in Callen's Thermodynamics)
  • · Replies 5 ·
Replies
5
Views
596
Undergrad Paradox: Thermodynamic equilibrium does not exist in gravitational fields
  • · Replies 135 ·
5
Replies
135
Views
8K
Undergrad Concept of Thermal Equilibrium in the Context of Canonical Ensemble
  • · Replies 5 ·
Replies
5
Views
3K
Undergrad A paradox about energy balance and steady state
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Request for an example of minimum energy principle (thermodynamics)
  • · Replies 2 ·
Replies
2
Views
1K
Undergrad Is Entropy the inexorable conversion of potential to kinetic energy?
  • · Replies 17 ·
Replies
17
Views
3K
Partial derivatives of thermodynamic state functions
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Thermodynamic functions and state variables
  • · Replies 8 ·
Replies
8
Views
1K
Undergrad Minimization of thermodynamic equilibrium
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad How Can Internal Energy of the Canonical Ensemble Change (Fluctuate)?
  • · Replies 15 ·
Replies
15
Views
2K