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carbon cycle
Cycle m du carbone

Carbon cycle. Whenever an animal breathes or burns fuel, carbon dioxide is released into the atmosphere. The process of photosynthesis constantly takes carbon dioxide from the atmosphere to build plant structures with it.

In this process carbon dioxide circulates around the Earth. There are dissolved stocks of it in oceans, lakes and rivers, in carbonate rocks and in fossil fuels. Below is a simple diagram of these movements. Some changes occur quickly, such as combustion, and others occur very slowly, such as the formation of rocks.

Marine animal shells
Decay
Carbonate rocks - CO2 in water in the form of HCO3
Heating - CO2 in the atmosphere
Photosynthesis
burning
plants
Breathing
Food decay
fossil fuel
animals


carbon dating
Description in the carbon - 14

Carbon dating. Carbon has a radioactive isotope (14/6C), and carbon dioxide contains a small, fixed percentage of this isotope. All carbon compounds found in living tissue contain this carbon-14 isotope in the same fixed ratio. When an animal or plant dies, this percentage decreases at a known rate. It decreases because the plant stops taking the isotope through photosynthesis and because the animal stops taking the isotope by eating the plant. The isotope begins to decay over time. By measuring the amount of radioactivity in dead material, its age can be estimated
Subject. Archaeologists use this technique.


carbonate(-CO3)
carbonate m

The carbonate group has a valence of two. Mineral carbonates are widely found in nature, such as limestone (CaCO3), dolomite (2(CaMg)(CO3)) and malachite (2(CCOC(OH). Calcium carbonate plays a role in the carbon cycle and is not insoluble.) Of carbonates of metals (except group 1 metals) in water. All carbonates produce carbon dioxide when heated strongly (2CO3 NaCO3) with difficulty and when treated with dilute acid. Carbonates are tested by adding acid to the solid compound and passing the resulting gas through lime water Lime water. Precipitate, which appears as a milky substance, indicates that the solid is carbonate.


catalysis
catalyse f

Mediation. See catalyst.


catalyst
catalyzer m

Mediator. A substance that changes the rate or speed of a chemical reaction. At the end of the reaction, the mediator remains as it was at the beginning, and the process is called catalysis.
Transition metals and their compounds are often useful intermediates. Here are some examples:

Interaction - mediator

Haber process
Iron

Contact process
Vanadium Oxide (V205) (V)

Ammonia - nitric acid
Platinum-rhodium alloy

Hardening fats
Nickel

All chemical processes that take place within the bodies of animals and plants depend on intermediates. These organic media are called enzymes.


cathode
cathode f

Helipad. The negatively charged electrode in a battery or electrolysis cell. Positively charged ions (stalactites) are attracted to the cathode during electrolysis, where they gain electrons.