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.
Answer:
Biological species.
Explanation:
Various concept like morphology species concept, ecological species concept was introduced by the scientists to explain the biological species. The biological species concept is accepted today.
The biological species concept explains that the group of interbreeding population that has the ability to reproductively isolated from the other such group.
Thus, the correct answer is option (c).
Nucleic acids is what it would be known as
Answer:
scientist Robert Hooke
Explanation:
Interested in learning more about the microscopic world, scientist Robert Hooke improved the design of the existing compound microscope in 1665. His microscope used three lenses and a stage light, which illuminated and enlarged the specimens.
Fimbriae is the word you're looking for
