Mantle convection describes the movement of the mantle as it transfers heat from the white-hot core to the brittle lithosphere. ... Convection currents also transfer denser, cooler material from the crust to Earth's interior through the process of subduction.Aug 11, 2015
Explanation:
a living system is a system in an organism consisting of organs. each organs carry out different functions to ense life processes can be carried out effectively. The function of the organs are determined by the cells which make up the tissues. The connections are important to remove wastes/toxins out of the body and help absorb nutrienys, in some cases produce hormones as a form of homeostasis to ensure the body remains in a healthy optimised state constantly.
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.
Two key characteristics of a good scientific investigation are hypothesis and observation of whatever organism your studying.
