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.
Hello, Leah082656. There are many heated arguments over discussing stem cell research because of these two moral principals: the duty to prevent or alleviate suffering and the duty to respect the value of human life. In order to get embryonic stem cells, the embryo has to be destroyed. Although this is a huge controversial problem, by researching this could actually save and treat many other people. Some people are for it because it saves multiple people in the process, and some do not like this because it is killing an embryo. Whatever your stance is on this debate, these are the two sides that people debate over. I hope I helped!! Have a great day. :)
Answer;
D. Most of the energy from photosynthesis flows out as heat
Explanation;
Energy flow is the amount of energy that moves through a food chain in a given ecosystem.
Producers such as green plants in a ecosystem convert energy from the the sun into carbon bonds, such as those found in the sugar glucose through the process of photosynthesis.
The amount of chemical energy storied as nutrients in the bodies and wastes of organisms flows through ecosystems from one trophic level to the next and through this flow energy also is lost as heat. And the chemical energy available to the succeeding feeding level decreases.
