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:
One method used by newborn mammals to generate heat is referred to as nonshivering thermogenesis. This method utilizes a protein channel called <u>thermogenin</u> which is present in high levels inside the mitochondria of <u>brown adipose tissue.</u>
Explanation:
Thermogenin forms a proton channel in the inner mitochondrial membrane in the brown adipose tissues. Most of the newborn mammals have these brown adipose tissues. In these tissues, the oxidation of nutrients do not produce ATP but generate heat. The heat is used by the newborn to maintain the warmer body temperature. The process is called nonshivering thermogenesis.
Answer:
In order for a fracture to heal, the bones must be held in the correct position and protected. Soon after a fracture occurs, the body acts to protect the injured area, and forms a protective blood clot and callus around the fracture. New "threads" of bone cells start to grow on both sides of the fracture line.
Explanation:
Answer:
leave the faucet on overnight
use the bathtub instead of the shower
take long showers
Explanation:
Probability is the measure of the likeliness that an event will occur. So.. probability.
