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 three fatty acids can be different from one another. Since the hydrocarbon chains are very non-polar, fats do no dissolve in water; instead, fat molecules tend to coalesce with one another. Since a fat molecule has 3 fatty acids connected to a glycerol molecule, they are also called triglycerides.
Answer:
if you water a plant the water travels though the soil then it will feed the roots and then it will go to the leaves of the plant.
Explanation:
Answer;
-Disruptive selection
Disruptive selection results in the creation of two distinct phenotypes.
Explanation;
-Disruptive selection is a type of natural selection that selects against the average individual in a population. The make up of this type of population would show phenotypes of both extremes but have very few individuals in the middle.
-The variance of the trait increases and the population is divided into two distinct groups. The disruptive selection will cause organisms with intermediate traits to reproduce less, and will allow those organisms with extreme traits to reproduce more.
