Month: December 2016

Change in Enthalpy

Change in Enthalpy

Change in Enthalpy

12/04/16

“How can we measure the change of energy in a thermodynamic system when the system itself changes?”

 

All thermodynamic systems have the summation of the parts of their energy represented by enthalpy. However, the universe is almost never in a static state, and is always changing. Consequently, all thermodynamic systems will be in perpetual change as well. And it turns out that this change in enthalpy has very practical results for scientific use. A change in enthalpy can be quantitatively described by taking the difference of the enthalpy of the system after the change and before the change. If the  enthalpy has gone up, then that means that energy must have been added to the system, making it an endothermic process. If the enthalpy has gone down, then heat was removed from the system and it was an exothermic process. The change in Enthalpy is often symbolically represented using a (delta)H

Enthalpy

Enthalpy

Enthalpy

12/03/16

“How can we model the total energy inside a thermodynamic system?”

 

As a scientist or engineer, if you ever work with thermodynamics systems, then you will have to understand the amount of energythat you are working with. However, how can we represent this concept in more concrete terms? Well, luckily for us, after many years of hard labor, scientists and engineers have formulated the very concept of enthalpy of this very matter. Enthalpy can be defined as the amount of energy stored within a thermodynamic system, which can be symbolically defined as H = u + p*V, with H being the enthalpy, u being the internal energy of the system, p being the pressure and V being the volume.

Energy density and it’s importance

Energy density and it’s importance

Energy density and it’s importance

12/02/16

“How do scientists and engineers measure the density of energy within a system and why is it important?”

Energy is a quantity that is used omnipresently for calculations in all branches of science and engineering. However, energy is more than a theoretical abstraction, and since it is tied to the material universe, it must be stored somewhere in reality, such as in objects. And since objects of the same size can have different abilities to hold energy , we will need some conceptual way to understand this. As a result, scientists and engineers have developed the concept of energy density to represent the amount of energy stored within in object. Energy density is an important concept because when analyzing energy storage mechanisms such as batteries and capacitors, once must take in to consideration the volume vs power limitations that a project might have. To illustrate, let’s say that you want to build an autonomous boat. Since this boat will have no people on board, it will need a mechanism to power it’s systems. However, the boat can not uphold too much weight, or else it will sync. Therefore, when designing such a contraption, engineers will have to choose an energy storage technology with a high energy density.

Ion-dipole forces

Ion-dipole forces

Ion-dipole forces

11/27/16

“What exactly causes ionic compounds to be dissolved in dipole solvents?”

 

One of the first facts one will learn in a Chemistry course is that ionic compounds such as salt (NaCl) will dissolve in dipolar solvents. However, have you ever wondered why does this phenomena take place? Well, as scientifically minded people, we should explore anything that we don’t know. Ionic compounds are held together by ionic bonds, which are the result of two or more atoms sharing electrons. And since these ionic bonds depend upon factors of charge distribution, they susceptible to the influence of external electric forces. As such, if they come into close contact to polar substances such as dipole solvents, the resulting ion-dipole force would rip apart the compounds.