CHEMISTRY GLOSSARY

unsaturated solution    →   nezasićena otopina

Unsaturated solution is a solution that contains less than the maximum possible equilibrium concentration of a solute.

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.

volume concentration    →   volumenska koncentracija

Volume concentration (σ) is equal to volume (V_A) of solute and volume (V) of solution proportion. Volume concentration differs from volume fraction because the sum of solution components volume is almost always different than the solution volume.

volume fraction    →   volumenski udio

Volume fraction (φ_A) is defined as

where V_A is the volume of the specified component and the V_i are the volumes of all the components of a mixture prior to mixing.

Winkler’s method    →   Winklerova metoda

Winkler’s method was once a common method used to determine the dissolved oxygen concentration by titration. Now rarely used due to the accuracy and low price of oxygen meters.

The water sample is first treated with excess manganese(II) sulfate solution and then with an alkaline solution of potassium iodide. The Mn(OH)₂ initially formed reacts with the dissolved oxygen. The amount of MnO(OH)₂ formed is determined by reaction with iodide ion in acidic solution. The iodine formed may be titrated against standard thiosulfate solution, using starch as an indicator.

abrasive    →   abraziv

Abrasive is a very hard, brittle, heat-resistant substance that is used to grind the edges or rough surfaces of an object. Boron carbide, diamond, and corundum are abrasive.

absorbance    →   apsorbancija

Absorbance (A) is a logarithm of the ratio of incident radiant power (P_o) to transmitted radiant power (P) through a sample (excluding the effects on cell walls).

The absorption of light by a substance in a solution can be described mathematically by the Beer-Lambert law

where A is the absorbance at a given wavelength of light, ε is the molar absorbtivity or extinction coefficient (L mol^-1 cm^-1), unique to each molecule and varying with wavelength, b is the length of light path through the sample (cm), and c is the concentration of the compound in solution (mol L^-1).

absorbed dose    →   apsorbirana doza

For any ionising radiation, absorbed dose (D) is the mean energy imparted to an element of irradiated matter divided by the mass of that element.

absorption    →   apsorpcija

Absorption is a phenomenon that occurs when matter crosses from one phase to another passing through the border surface and in the other phase more or less monotonously distributes itself in a concentration higher than the one within the first phase.

activator    →   aktivator

Activator is a substance that increases the activity of a catalyst; for example, a substance that - by binding to an allosteric site on an enzyme - enables the active site of the enzyme to bind to the substrate.