CHEMISTRY GLOSSARY

dysprosium    →   disprozij

Dysprosium was discovered by Paul Emile Lecoq de Boisbaudran (France) in 1886. The origin of the name comes from the Greek word dysprositos meaning hard to obtain. It is soft, lustrous, silvery metal. Reacts with oxygen. Reacts rapidly with water; dissolves in acids. Metal ignites and burns readily. Reductant. Dysprosium usually found with erbium, holmium and other rare earths in some minerals such as monazite sand. Dysprosium uses are limited to the experimental and esoteric. Some isotopes of dysprosium are effective absorbers of thermal neutrons and are being considered for use in the control rods in nuclear reactors.

EDTA    →   EDTA

Ethyldiaminetetraacetic acid (C₁₀H₁₆N₂O₈) or shortened EDTA is a hexadentant ligand, and it forms chelates with both transition-metal ions and main-group ions. EDTA is used as a negative ion - EDTA^4-. The diagram shows the structure of the ion with the important atoms picked out. The EDTA ion entirely wraps up a metal ion using all 6 of the positions. The co-ordination number is again 6 because of the 6 co-ordinate bonds being formed by the central metal ion.

EDTA is frequently used in soaps and detergents, because it forms a complexes with calcium and magnesium ions. These ions are in hard water and interfere with the cleaning action of soaps and detergents. EDTA is also used extensively as a stabilizing agent in the food industry and as an anticoagulant for stored blood in blood banks. EDTA is the most common reagent in complexometric titration.

Einstein equation    →   Einsteinova jednadžba

Einstein equation is the mass-energy relationship introduced by Albert Einstein in 1905 in the form E = mc², where E is a quantity of energy, m its mass, and c is the speed of light. It presents the concept that energy possesses mass.

Einstein, Albert    →   Einstein, Albert

Albert Einstein (1879-1955) is a German born American physicist, who took Swiss nationality in 1901. A year later he went to work in the Bern patent office. In 1905. he published five enormously influential papers, one on Brownian movement, one on the photoelectric effect, one on the special theory of relativity, and one on energy and inertia (which included the famous expression E = mc²). In 1915 he published the general theory of relativity, concerned mainly with gravitation. In 1921 he was awarded the Nobel Prize. In 1933, as a Jew, Einstein decided to remain in the USA (where he was lecturing), as Hitler had come to power. For the remainder of his life he sought a unified field theory. In 1939 he informed president Roosevelt that an atom bomb was feasible and that. Germany might be able to make one.

pesticide    →   pesticid

Pesticides are chemical means against pests in agriculture. They are used for annihilation of weed (herbicides), insects (insecticides) and funguses (fungicides). They have a toxic effect on man and are the most frequent cause of food pollution.

plastic welding    →   varenje plastike

Plastic welding is the fusion of two pieces (usually of the same plastic type) with a directed hot air jet and plastic welding rod. Used increasingly for the manufacture of tanks, floats and other items. Useful for repair of pipework (either temporary or permanent).

potassium fertilizer    →   kalijevo gnojivo

Potassium fertilizers are compounds of potassium used as an artificial manure e.g. potassium-chloride, potassium-sulphate, potassium-magnesium-sulphate, and ashes formed after wood burns out.

potassium glass    →   kalijevo staklo

Potassium glass is a type of glass produced from potassium silicates and calcium with potassium carbonate. It dissolves harder than regular glass and it is used in production of chemical vessels.

electrodeposition    →   elektrodepozicija

Electrodeposition is a process of depositing solid materials on an electrode surface using electrolysis. It is a somewhat loosely used term that is applied to many technologies. There are a number of metal deposition technologies. However, not only metals but also different compounds can be electrodeposited. This is used most often for the formation of oxides (such as manganese dioxide and lead dioxide) by anodic oxidation of dissolved salts.

electrolytic cell    →   elektrolitska ćelija

Electrolytic cell is an electrochemical cell that converts electrical energy into chemical energy. The chemical reactions do not occur spontaneously at the electrodes when they are connected through an external circuit. The reaction must be forced by applying an external electric current. It is used to store electrical energy in chemical form (rechargeable battery). It is also used to decompose or produce (synthesise) new chemicals by the application of electrical power. This process is called electrolysis, e.g., water can be decomposed into hydrogen gas and oxygen gas. The free energy change of the overall cell reaction is positive.