A Energy diagram Is a graph of energy that illustrates the process that occurs throughout a reaction. The energetic diagrams can also be defined as the visualization of an electronic configuration in orbitals; Each representation is an electron of an orbital with an arrow.
For example, in an energetic diagram the arrows pointing in the upper direction represent an electron with a positive spin. In turn, the downward-pointing arrows represent an electron with a negative spin.
There are two types of energy diagrams. Diagrams of thermodynamics or organic chemistry, which show the amount of energy generated or spent throughout a reaction; Starting from the elements are found as reactive, passing through a state of transition, to the products.
And the diagrams of inorganic chemistry, which serve to demonstrate the molecular orbitals according to the level of energy that atoms have.
Types of energy diagrams
Thermodynamics diagrams
The thermodynamic diagrams are diagrams used to represent the thermodynamic states of a material (typically fluids) and the consequences of the manipulation of this material.
P For example, an entropic temperature diagram can be used to demonstrate the behavior of a fluid as it changes through a compressor.
Sankey's diagram
Sankey diagrams are energetic diagrams in which the thickness of the arrows are shown in proportion to the amount of flow. An example can be illustrated as follows:
This diagram represents the entire primary energy flow of a plant. The thickness of the bands is directly proportional to the energy of production, use and losses.
The primary sources of energy are gas, electricity and coal / oil and represent the energy input to the left side of the diagram.
You can also visualize energy costs, material flow at regional or national level, and the breakdown of the cost of an item or services.
These diagrams place a visual emphasis on large power transfers or flows within a system.
And they are very useful in locating dominant contributions in a general flow. Often these diagrams show quantities conserved within the boundaries of a defined system.
P-V diagram
It is used to describe changes corresponding to the volume and pressure measurements in the system. They are commonly used in thermodynamics, cardiovascular physiology and respiratory physiology.
P-V diagrams were originally called diagrams. They were developed in the 18th century as tools to understand the efficiency of steam engines.
A diagram P-V shows the change in pressure P with respect to the volume of V of some process or processes.
In thermodynamics, these processes form a cycle, so that when the cycle is completed there is no change in the state of the system; As for example in an apparatus which returns to its initial pressure and volume.
The figure shows the characteristics of a typical P-V diagram. A number of listed states (1 through 4) can be observed.
The path between each state consists of some process (A to D) that alters the pressure or volume of the system (Or both).
Diagram T-S
It is used in thermodynamics to visualize changes in temperature and specific entropy during a thermodynamic process or cycle.
It is very useful and a very common tool in the area, particularly because it helps visualize the heat transfer during a process.
For reversible or ideal processes, the area under the T-S curve of a process is the heat transferred to the system during that process.
An isentropic process is plotted as a vertical line on a T-S diagram, while an isothermal process is plotted a horizontal line.
This example shows a thermodynamic cycle taking place in a hot tank temperature Tc, and a cold tank temperature Tc. In a reversible process, the red area Qc is the amount of energy exchanged between the system and the cold tank.
The blank area W is the amount of energy work exchanged between the system and its surroundings. The amount of heat Qh exchanged between the hot reservoir is the sum of the two.
If the cycle moves to the right it means that it is a heat engine that releases work. If the cycle moves in the opposite direction, it is a heat pump that receives work and moves the heat Qh from the cold tank into the hot tank.
Inorganic chemistry diagrams
They serve to represent or outline the molecular orbitals related to atoms and their energy level.
Potential energy diagram of ethane
The different conformations of ethane will not have the same energy since they have a different electronic repulsion between hydrogens.
As the molecule is rotated, starting from an already alternating conformation, the distance between the hydrogen atoms of the particular methyl groups begins to decrease. The potential energy of that system will increase until it reaches an eclipsed conformation
The different types of energy can be represented graphically between the various conformations. In the diagram of ethane it is observed how the eclipsed conformations are the maxima of energy; On the other hand the alternates would be the minimums.
In this diagram of potential energy ethane starts from an eclipsed conformation. Turns are then made from 60 ° to 60 ° until 360 ° are crossed.
The different conformations can be classified according to energy. For example, alternates 1,3 and five have the same energy (0). On the other hand, the conformations 2,4 and 6 will have more in energy as a result of the hydrogen-hydrogen eclipses
References
- Pressure volume diagram. Retrieved from wikipedia.org
- T-S diagram. Retrieved from wikipedia.org
- Sankey diagram. Retrieved from wikipedia.org
- Potential energy diagrams. (2009). Recovered from chemicaorganica.net