CHEMISTRY GLOSSARY

transference number    →   prijenosni broj

Transference number of an ion is the fraction of the total current that is carried by that ion during electrolysis. Different ions carry different fractions of the current because different ions move at different speeds under the same potential gradient. In general, a cation and an anion differ in the amount of current they can carry during electrolysis.

gasoline    →   motorni benzin

Gasoline is a complex mixture of volatile hydrocarbons that may have between 5 to 12 carbons. The major components are branched-chain paraffins, cycloparaffins, and aromatics. Gasoline is most often produced by the fractional distillation of crude oil as the fraction of hydrocarbons in petroleum boiling between 30 °C and 200 °C. The quality of a fuel is measured with its octane number. Octane number is the measure of the resistance of gasoline against detonation or preignition of the fuel in the engine. The higher the octane number, the more compression the fuel can withstand before detonating. The octane number is determined by comparing the characteristics of a gasoline to isooctane with good knocking properties (octane number of 100) and heptane with bad (octane number of 0).

lead    →   olovo

Lead has been known since ancient times. The origin of the name comes from the Latin word plumbum meaning liquid silver. It is very soft, highly malleable and ductile, blue-white shiny metal. Tarnishes in moist air; stable in oxygen and water. Dissolves in nitric acid. Compounds toxic by inhalation or ingestion. Danger of cumulative effects. Lead is found most often in ores called galena or lead sulfide (PbS). Used in solder, shielding against radiation and in batteries.

mass    →   masa

Mass (m) is the quantity of matter contained in a particle or body regardless of its location in the universe. Mass is constant, whereas weight is affected by the distance of a body from the centre of the Earth (or of other planet). The SI unit is kilogram.

According to the Einstein equation

all forms of energy possess a mass equivalent.

vapour pressure lowering    →   snižavanje tlaka pare

Vapour pressure is a colligative property of solutions. The vapour pressure of a solution is always lower than the vapour pressure of the pure solvent. Ratio of solution to pure solvent vapour pressures is approximately equal to the mole fraction of solvent in the solution.

molality    →   molalitet

Molality or molal concentration (b; formerly m) is a concentration in which the amount of solute is stated in moles and the amount of solvent in kilograms.

The unit of molality is mol kg^-1.

Nernst’s division law    →   Nernstov zakon razdjeljenja

Nernst’s division law states that a substance is divided between two solvents in a way that proportion of concentrations of that substance is at certain temperatures constant, under the condition that both solvents are in the same molecular state. Division coefficient is a proportion of substance concentration in solvents A i B at a defined temperature.

Appearance of division is used for substance extraction.

palladium    →   paladij

Palladium was discovered by William Hyde Wollaston (England) in 1803. Named after the asteroid Pallas which was discovered at about the same time and from the Greek name Pallas, goddess of wisdom. It is soft, malleable, ductile, silvery-white metal. Resists corrosion; dissolves in oxidizing acids. Absorbs hydrogen. Metal dust is combustible. Palladium is obtained with platinum, nickel, copper and mercury ores. Used as a substitute for silver in dental items and jewellery. The pure metal is used as the delicate mainsprings in analog wristwatches. Also used in surgical instruments and as catalyst.

practical salinity    →   praktični salinitet

Practical salinity S_P is defined on the Practical Salinity Scale of 1978 (PSS-78) in terms of the conductivity ratio K₁₅ which is the electrical conductivity of the sample at temperature t₆₈ = 15 °C and pressure equal to one standard atmosphere, divided by the conductivity of a standard potassium chloride (KCl) solution at the same temperature and pressure. The mass fraction of KCl in the standard solution is 0.0324356 (32.4356 g of KCl in 1 kg of solution). When K₁₅ = 1, the Practical Salinity P S is by definition 35. The conductivity of that reference solution is C(35,1568,0) = 42.914 mS/cm = 4.2914 S/m (Siemens per meter). Note that Practical Salinity is a unit-less quantity. Though sometimes convenient, it is technically incorrect to quote Practical Salinity in "psu". When K₁₅ is not unity, S_P and K₁₅ are related by the PSS-78 equation

At a temperature of t₆₈ = 15 °C, R_t is simply K₁₅ and Practical Salinity S_P can be determined from the above equation. For temperatures other than t₆₈ = 15 °C, Practical Salinity S_P is given by the following function of R_t (k = 0.0162)

relative density    →   relativna gustoća

Relative density (d) is the ratio of the density of a substance to the density of some reference substance. For liquids or solids it is the ratio of the density (usually at 20 °C) to the density of water at 4 °C. Since one must specify the temperature of both the sample and the water to have a precisely defined quantity, the use of this term is now discouraged. This quantity was formerly called specific gravity.