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.
Phagocytes are the type of cells that 'devour' foreign cells in order to protect the body using phagocytosis.
Answer: Increase in compactness of the material.
Explanation:
Evaporites are the sedimentary rocks that are formed by the sediments and brines of the materials being degraded or withered from the parent and pre-existing rocks. The water is also lost from the withered material due to evaporation. The borax and gypsum also lose water to become evaporites and the increase in compactness due to loss of water molecules and increase in intramolecular forces between solid substances in the rock helps in sedimentation of the rock.
<span>1. c) Exposure would weaken the body’s immune system and leave it unable to fight future infections.
</span>2. <span>c) Excess amounts are removed by the kidneys and excreted along with urine.</span>
Answer:
On the Moon, regolith occurs as a mixture of powdery dust and broken rock. Lunar regolith is formed by the impact of meteorites on the body's surface. The force of the collision melts some of the impacted regolith to form objects known as agglutinates and heaves debris (ejecta) outward from the point of impact. need brainliest pls
Explanation:
