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:
The moon is earths only permanent natural satellite
the moon always shows earth the same face
the sun and moon are not the exact size
the moon is 238,900 miles from earth
the moon is estimated to be about 4.6 billion years old
According to sources, the most probable answer to this query is that nephrons found in the kidney are responsible for filtering out waste in the blood cells. The resulting product is urea.
This is then excreted to the body.
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Answer:
To regenerate damaged tissue
Explanation:
Stem cells can be pluripotent, totipotent or multipotent depending on where they are sourced. This means that they are capable of differentiating into a wide variety of cells. Stem cells can, therefore, be harvested and induced to differentiate into cells or tissues that are intended to be repaired.
It is because it's surface area is responsible for the production of ATP molecules.
