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acid salts
Sels mpl acides

Acidic salts. Salts in which the metal replaces some replaceable hydrogen atoms in an acid molecule. Here are some examples:

NaHCO3 Sodium hydrogen carbonate
Sodium carbonate Na2CO3

NaHSO4 sodium sulfate
Sodium sulfate Na2SO4

Na2HPO4 sodium hydrogen phosphate
Sodium phosphate Na3PO4


acid oxides
oxydes mpl acides

acidic oxides. Most oxides react
Nonmetals combine with water to form acidic solutions. That's why solutions are known as
Acidic oxides. For example:

Oxide
CO2 carbon dioxide
SO sulfur dioxide
SO sulfur trioxide

Acid
H2CO3 is a carbonic acid
H2SO3 Sulfuric acid
H2SO4 Sulfuric acid


activation energy (Ea)
energie f d'activation

Activation energy When hydrogen and oxygen mix, no reaction occurs between them. When a flame is placed within the mixture of two gases, an immediate explosion occurs. The heat of the flame causes the reaction to occur. There are many similar chemical reactions. It seems that there is a barrier that must be crossed before the reaction occurs. Energy (i.e., the heat of the flame) must be introduced in order for the reaction to occur.
This energy is called activation energy.
See catalyst.

Energy barrier. It must be bypassed
Activation energy
Reactants
products

addition reaction
Reaction f d'addition

Dammam reaction. Two or more molecules interact to form a single molecule. There are good examples of this in the reactions of alkenes. These compounds contain double bonds and can add an atom to each side of the double bond to form saturated alkanes. Here we include an example of the reaction of ethene
With hydrogen.

Combining reactions also occur when many polymers, i.e. poly(ethene), are made.


air. air
air m

Air is a mixture of gases surrounding the Earth. The average composition of fresh air is shown below. This composition varies from place to place and according to height.

(20.9%) oxygen
(0.9%) argon
(0.03%) carbon dioxide
(78.1%) nitrogen

other ingredients :
Neon, helium, krypton, xenon - in small, constant quantities.
Water - in highly variable quantities.

The air also contains pollutants, some of which are listed below:


Pollutant - source

Sulfur dioxide - combustion of coal and oil
Carbon monoxide - engines and cigarettes
Nitrogen oxides - automobile engines
Bloat – Fires and engines
Pollen – trees and flowers
Dust - volcanoes

Air is essential for life. Oxygen is necessary for respiration, while photosynthesis requires carbon dioxide.

alcohols
alcools mpl

alcohol. Alcohol of all kinds is important organic compounds. Alcohol contains the following arrangement of atoms:

The OH group is the functional group for alcohols, and ethanol is the most important compound, but see also methanol and glycol. Alcohols with relative molecular mass Mr. Flammable liquids that dissolve in water. One of the important properties of alcohols is that they are easily oxidized, form esters, and react with sodium to produce hydrogen and hydrogen.