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:
Oxygen is used to break down sugar and sugars release energy
Answer:
Enzymes function best at specific pH and temperatures.
Explanation:
An enzyme can be defined as a biological catalyst that typically lowers the activation energy of a biological reaction. When the activation energy of a reaction is low, the rate of the reaction would be faster. Therefore, an enzyme speeds or catalyzes the rate of a reaction by lowering its activation energy.
Also, if the conditions are not optimal for an enzyme, it limits the ability of an enzyme to bind or be joined with its substrates.
Hence, the correct statement about enzymes is that enzymes function best at specific pH and temperatures. An increase in temperature increases or speeds up the rate of a reaction while low temperature limits or reduces the rate of a reaction. The optimal temperature for enzymes in the human body is around 37 degrees celsius.
Answer:
pushing iron out
Explanation:
Excess iron will be push out of the cell to regulate the internal environment of cell, this active transport involve osmosis.
if this type of reaction occur in a plant cell, the plant cell will shrink which may/will leads to death of the plant.
Hope it is helpful
don't mind my grammatical blunders.
Thank you.
Answer:
Independent assortment is random and occurs during Metaphase I of meiosis. There are two possible alignments for the chromosomes.
