Why is entropy defined as a state property?

In summary, the conversation discusses the concept of entropy and its definition by Clausius. The main point is that entropy is a state property, meaning it can be predicted by knowing its value at a specific moment rather than the entire history. This is in contrast to variables like work, which depend on the path taken. Clausius also discovered the concept of an integrating factor, which is a mathematical tool used to solve certain equations.
  • #1
thedy
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Hi,I m just beginner in physics,but actually I don need exact expression of physical laws in math language.I know,math is language of physics but still...
So,I m looking for answer to my questions about origin of Clausius s entropy.
I this article: http://www.panspermia.org/seconlaw.htm is written,that Clausius decided define entropy,because q/T was constant.And my question is:Why only constant ratios are some physical properties?What does it mean to be constant property in nature.It is quite bit physical,but for my starting point,I just want to know,what is physical view,how physics works...
So,if you can,try exaplain me,why constant ratios can be assumed to be property and why not all constant ratios are physical quantity.Why Clausius decided to define ratio q/T to be entropy?
THanks a lot
 
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  • #2
The key achievement is that entropy defined by Clausius dS=dQrev/T is a state property.

In general, you can imagine that to predict what is going to happen next, you need to know everything that happened before. However, the special property of a state variable is that to make a prediction, you just need to know it at one moment in time. (That's the rough idea.)

An example of something that isn't a state property is the work done on an object - that depends on the path through which you moved an object.

Mathematically, he discovered what is called an "integrating factor". http://en.wikipedia.org/wiki/Integrating_factor
 

1. What is the significance of Clausius' entropy in thermodynamics?

Clausius' entropy is a fundamental concept in thermodynamics that quantifies the amount of disorder or randomness in a system. It helps us understand the direction of heat flow and the efficiency of energy conversion processes.

2. Who was Clausius and how did he develop the concept of entropy?

Rudolf Clausius was a German physicist who is credited with formulating the concept of entropy in the mid-19th century. He noticed that heat always flows from hot to cold objects and proposed that this flow is due to the tendency of systems to increase their disorder over time.

3. How is entropy related to the second law of thermodynamics?

The second law of thermodynamics states that the total entropy of a closed system will always increase over time. This means that energy will naturally spread out and become more evenly distributed, leading to an increase in disorder or entropy.

4. Can entropy be reversed or decreased?

Entropy can only be decreased in a system if energy is actively put into it. This is because the natural tendency of systems is to increase their disorder and reach a state of maximum entropy.

5. How is entropy measured and calculated?

Entropy is measured in units of joules per kelvin (J/K). It can be calculated using the formula S = Q/T, where S is the entropy, Q is the amount of heat transferred, and T is the temperature in kelvin. This formula is based on the idea that heat will spontaneously flow from a hot object to a cold one, increasing the system's entropy in the process.

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