Fuel cells can make an electricity from a simple electrochemical
reaction in which oxygen and hydrogen combine to form water. There are several
different types of fuel cell but they are all based around a central design
which consists of two electrodes, a negative anode and a positive cathode.
These are separated by a solid or liquid electrolyte that carries electrically
charged particles between the two electrodes. A catalyst, such as platinum, is
often used to speed up the reactions at the electrodes. Fuel cells are
classified according to the nature of the electrolyte. Every type needs
particular materials and fuels and is suitable for any applications. The
article below uses the proton exchange membrane fuel cell to illustrate the
science and technology behind the fuel cell concept but the characteristics and
applications of the other main designs are also discussed. Proton Exchange Membrane Fuel Cells (PEMFC)
The hydrogen ions permeate across the electrolyte to the
cathode, while the electrons flow through an external circuit and provide
power. Oxygen, in the form of air, is supplied to the cathode and this combines
with the electrons and the hydrogen ions to produce water. These reactions at
the electrodes are as follows:
Anode: 2H24H+ + 4e-
Cathode: O2 + 4H+ + 4e- 2H2O
Overall: 2H2 + O22H2O + energy
PEM cells operate at a temperature of around 80°C. At this
low temperature the electrochemical reactions would normally occur very slowly
so they are catalysed by a thin layer of platinum on each electrode.
Hola amigo mi no hablas ingles mi only hablas español
Anything prokaryotic doesn't contain a nucleus
In a clinical situation where it is essential to control microbial growth that includes both mycobacteria and endospores, the chemical <span>agent that would be the most effective to guarantee the broadest disinfection are chlorines.
Chlorine (Cl) is a yellow-green gas often used for disinfection in its liquid form. </span>
Answer:
Graves´ disease is an autoinmmune disease that is caused when the immune system attacks the cells of the thyroid gland, which leads to an overproduction of the hormones secreted by the thyroid gland. This constant attack and destruction on the part of the immune cells causes the thyroid to increase in size, a condition that is commonly known as hyperthyroidism.
Hyperthyroidism can become a really serious issue because the excessive production of the hormones of the thyroid gland will increase the metabolic activity of all parts of the body and can, if left untreated, cause such serious conditions as blood clotting problems, type 1 diabetes, among others.
