What is the physical interpretation of enthelpy and entropy?

In summary, Thermodynamics is a field of physics that studies the effects of heat on matter. It explains the physical interpretation of enthalpy and entropy and how every reversible process must be adiabatic. Clausius inequality measures the entropy of a cyclic process and states that the sum of Q/T is zero, if it is reversible, and less than zero, if it is irreversible. Q-W=U is for closed system and Q-W= enthalpy + KE + PE is for steady state open system.
  • #1
mune
19
0
Hi guys, I need help on thermodynamics:

1. what is the physical interpretation of enthalpy and entropy?

2. in an open system, change in total energy = change in enthalpy?

3. every reversible process must be adiabatic?

4. what does clausius inequality means?

5. Q-W=U is for closed system? and Q-W= enthalpy + KE + PE is for steady state open system?

thanks
 
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  • #2
clasius equality means that net entropy of an isolated system increases.
 
  • #3
would you mind giving us your own attempts at answers to your questions?
 
  • #4
1. what is the physical interpretation of enthalpy and entropy?
enthalpy, U+PV, is the heat can be used to do work and entropy, dQ/T is a measure of randomness. but i still don't understand, what does a large change in enthalpy and a small change in enthalpy means physically? same for entropy.

2. in an open system, change in total energy = change in enthalpy?
this one i don't quite understand, i saw it in an example, wonder if it is always true.

3. every reversible process must be adiabatic?
because reversible process does not leave trace to environment, so i guess dQ=0, which is adiabatic. But I am not too sure about it.

4. what does clausius inequality means?
sum of Q/T of a cyclic process is zero, if it is reversible, and less than zero, if it is irreversible. but i don't know what is the use of this inequality, what does it implies? if it measures entropy, then why do we need to know change in entropy?

5. Q-W=U is for closed system? and Q-W= enthalpy + KE + PE is for steady state open system?
this one i knew the answer. yes and yes.

pls tell me if you know anyone of the answers. Thanks!
 
  • #5
i have informayion on it!
come and visit my blog and you will see half a page of it!
Thermodynamics
but I am not that sure if it will help
because i posted the info on differnt types of it.
ok , i'll try to help you research on the questions you asked.
 
Last edited:
  • #6
kaisxuans said:
i have informayion on it!
come and visit my blog and you will see half a page of it!
Thermodynamics
but I am not that sure if it will help
because i posted the info on differnt types of it.
ok , i'll try to help you research on the questions you asked.



will go to see it after a few minutes.

thanks.
 

FAQ: What is the physical interpretation of enthelpy and entropy?

What is the difference between enthalpy and entropy?

Enthalpy refers to the total energy of a system, including both its internal energy and the energy required to overcome external pressure. Entropy, on the other hand, refers to the measure of disorder or randomness in a system. In simpler terms, enthalpy is a measure of a system's energy, while entropy is a measure of its disorder.

How is enthalpy related to heat and work?

Enthalpy is closely related to heat and work. In a system, enthalpy can change through the transfer of heat or the performance of work. When heat is added to a system, its enthalpy increases, and when work is done on a system, its enthalpy also increases. Conversely, when heat is removed from a system or work is done by the system, its enthalpy decreases.

What is the physical interpretation of enthalpy?

The physical interpretation of enthalpy is the amount of energy required to create a system at constant pressure. It can also be thought of as the potential energy of a system, as it represents the maximum amount of work that can be done by the system.

How does entropy affect the spontaneity of a reaction?

Entropy plays a crucial role in determining the spontaneity of a reaction. The second law of thermodynamics states that the total entropy of an isolated system always increases over time. Therefore, a reaction that results in an increase in entropy is more likely to be spontaneous.

Can entropy be negative?

Yes, entropy can be negative. This occurs when a system becomes more ordered, such as when a gas condenses into a liquid. However, the overall change in entropy in a closed system must be positive according to the second law of thermodynamics.

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