What is Law of Thermodynamics ?
1. The two bodies in the thermal equilibrium are at the same temperature.
2. The energy cannot be created or destroyed.
3. The total entropy of the UNIVERSE is equal to the surrounding system and MUST INCREASE in every spontaneous process.
4. The entropy (S) of a pure, perfectly crystalline at compound at T = 0 K is ZERO.
* Thermodynamics is basically between system and the surrounding. The surrounding is including every else in this universe. Thermodynamics system can be explain in form of energy transfer which contain of three basic kind :
a) Isolated system :
* The system can exchange neither energy nor matter with an outside system.
- Example : A closed thermos bottle.
b) Close system :
* The system that can exchange energy but not matter with outside system.
-Example : Earth gains lot of energy from the Sun but the exchange of matter with outside is almost zero.
c) Open system :
* The systems which can exchange both matter and energy with an outside system.
- Example : The system of our body.
**** REMINDER : The heat can transferred between the open and closed systems, but not between the isolated system.
Can you think the EXAMPLES of this law of thermodynamics ?
First Law of Thermodynamic
- Energy can change from one to another, but it cannot be created nor destroy.
- But the energy can be converted from one to another. - Conclusion : Energy of the whole system is constant. *** When the external energy is applied to a system, then the internal energy of the system will be increase*** The equation of the first law is: ΔE = q + w ΔE : The internal energy change of the system. q : The heat transferred into / out of the system. w : The work done by / on the system. 1st Law of Thermodynamics tells us that the energy of the system will remain constant unless there have heat added or taken away from the system, or some work takes place. |
Second Law of Thermodynamics- State that a process that starts in equilibrium and finish with another will always tend to move to the direction in which the entropy increase.
- The potential energy will be less than the initial state if there is no energy enters or leaves the system in all energy exchanges. - It can referred to as entropy. " Entropy" is the measure of the "disorder" of a system. "Disorder" is referring to the number of different microscopic states of a system which it can be in, given that the system has a particular fixed composition, volume, energy, pressure, and temperature. - Conclusion : The heat cannot be converted without losing some of it amount. The equation of the first law is: ΔS = Δq/T ΔS : The change in entropy after a reaction has taken place. Δq : The change of heat in the system. T : Time taken for the reaction. - Pressure is the factor that affects the energy of a system. The equation below was created to relate the changes in entropy and enthalpy of reaction: ΔG = ΔH - (TΔS) ΔH : The change in energy after the reaction. ΔS : The change in entropy after the reaction. T : Time taken for the reaction to occur. |