Entropy and Enthalpy

Entropy and Enthalpy

Entropy is defined as one way process. It measure the disorder of a gas or a system can have. It is one way process because the amount of energy needed to cause a disorder on a system is much less than the amount of energy needed reverse the process. Indeed, it is almost or impossible to reserve a process. For example, the process in which chemical energy is transformed in mechanical is considered an irreversible process because when the gasoline is ignited to make the pieces inside the engine rotate to do mechanical work, it is impossible to reverse the process or working backwards.
Enthalpy is the amount of heat used or release from a system at constant pressure. Takes the same units as Q(heat) used to calculate the amount of heat needed to melt or fuse water into ice.

The first picture shows the two definitions. Entropy can be found using (heat (Q))/(temperature (T)), or (heat (Q))/(thermal energy (KT)). A few examples of Entropy are boiling water, burning staff, and the diffusion of a gas.

The next is the enthalpy that is represented with the letter H and is calculating by adding the internal energy of the system (U) plus pressure times delta V(volume) or work done on the system.

The two pictures that can be seen are simples calculations to help everyone to see what each of us is buying special when it comes to Air Conditioners.

Video

This video has the intention to show how by heating water, and use its vapor and balancing with ice, mechanical work can be done. The process is: water is heated until 100 degree Celsius, after that the recipient is placed under the small engine cylinder. Ice is place over the it to balance the temperature differences. Once the small engine gain enough vapor to start moving, it will transform the vapor into mechanical work. Yet, the reverse process does not occur because mechanical movement cannot be transformed into vapor. It is an example of an entropy process as one way process.     

This lab had the intention to make students aware that any phase transition of any system have only one way and they are not reversible. Otherwise the cost to make it would not compensate the transformation of any article in an useful tool. For example, it is possible to cut a tree and produce wood furniture. But it is impossible to reverse the process, pass the wood furniture in a tree.