أكاديميا - كولنز - معاجم الجيب العلمية - الكيمياء - انكليزي - فرنسي - عربي الحرف ١_ d

Academia - Collins - Pocket Scientific Dictionaries - Chemistry - English - French - Arabic Letter 1_ D


DC (or direct current)

DC current. A type of electrical current produced by a simple cell or battery, which is the only one that can be used in electrolysis.

DDT (or DichloroDiphenyl Trichloroethane)
DDT

Dr.. Dr.. T. A widely used pesticide that has successfully suppressed diseases such as malaria. But it also harms the life of animals because some animals concentrate it in their bodies, where it acts as a poison. Therefore, some countries have limited its use.


decant
decanter

Clap . Pour from a bowl. If the precipitate is allowed to settle, the remaining liquid can then be decanted by pouring it quietly without disturbing the solid.

decomposition
décomposition f

fell apart. The breakdown of compounds into simpler compounds or elements, a process that usually requires heat (decomposition
thermal), such as:

2CuO + 4NO2 + O2 → 2Cu(NO3)2

(solid)(gas) (gas)(solid)

(gas)02+ (liquid)2Hg < (solid)(2HgO)

(gas) CO2+ (solid) CaO - (solid) CaCO3


decrepitation
Decrepitation f

Break up. When some crystals are heated
A sharp cracking sound is heard, which is the sound of crystals disintegrating.
Lead nitrogenate (Pb(NO3)2) (II) is an example of a salt in which cleavage occurs.

dehydration agent
Deshydratant m

Dewatering agent. A substance used to remove water from other substances. Such substances are always attractive to water, and they can be substances that dissolve in water, such as:
Concentrated sulfuric acid H2SO4
Sodium hydroxide NaOH

Or substances that interact with water, such as:

Calcium oxide CaO
Which forms hydroxide
Ca(OH)2 ←

The third type of dewatering agent is anhydrous salt, which absorbs water, such as:

Calcium chloride CaCl2. CaCl2 → 2H2O

Sodium sulfate Na2SO4
Na2SO4. 10H2O←

Dewatering agents are used in desiccators.


deliquescence
déliquescence f

Sahaf. Soft materials can absorb water from the atmosphere. These materials can take amounts of water that turn them into solutions, unlike hygroscopic materials.
Common examples are:

Iron (III) chloride FeCl3
Copper (II) nitrate Cu(NO3)2
Calcium chloride CaCl2

Some fluffy materials are used in desiccators.


delocalized electrons
Electronics mpl non localized

Position-shifting electrons. Electrons are found in normal covalent bonds between two atoms, such as the carbon-carbon single bond, which consists of two electrons: C:C.

The double bond consists of four electrons: C::C
These electrons are located between the two atoms, and they are localized. But some materials contain electrons that move freely between atoms. These atoms are delocalized. Graphite contains variable location electrons within hexagonal layers of atoms. For this reason, graphite transmits electricity along the layers but not between them. Metals also have variable atoms, which explains why they are good conductors.


density density
density f

Density. Density of a substance is a measure of the space occupied by a certain amount of it. The smaller the space in which the mass is concentrated, the greater the density. The density of a substance, such as lead, for example, is determined by the density of the individual atoms and their proximity to each other, arranged in the crystal lattice.

In general, the more particles in an atom, the greater the density.
Density is calculated by dividing the mass of a substance by its volume. The unit of measurement may be g/cm or kg/m3.


desiccator
Dessiccateur m

dryer. Dryers are used to store materials that require a dry atmosphere, such as deliquescent or hygroscopic materials.

The dryer is tightly sealed and does not allow air to pass through. It contains a dehydrating agent that keeps the air dry.

Floor glass connection
cover
Stock material
Gauze
Dewatering agent such as anhydrous calcium chloride. (CaCl2)