CHEMISTRY GLOSSARY

mass fraction    →   maseni udio

Mass fraction (w_A) is the ratio of the mass of substance A to the total mass of a mixture.

fraction    →   udio

Fraction is a ratio of two quantities of the same kind, the numerator quantity applying to one constituent (or part) of the system and the denominator to the sum of quantities for all constituents (parts) of the system. When applied to mixtures fractions represent a group of three quantities: mass fraction, volume fraction and amount fraction (or mole fraction equal to the number fraction).

amount fraction    →   količinski udio

Amount fraction, x_A, (y for gaseous mixtures) is the ratio of the amount of substance (number of moles) of substance A to the total amount of substance in a mixture.

mass number    →   maseni broj

Mass number (A) is a characteristic property of a specific isotope of an element, equal to the sum of the number of protons and neutrons in the nucleus.

mass ratio    →   maseni omjer

Mass ratio is equal to the proportion of the mass of one (m_A) and the mass of other component (m_B).

molar fraction    →   molarni udio

See Amount fraction

mole fraction    →   molni udio

See Amount fraction

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.

mass concentration    →   masena koncentracija

Mass concentration (γ) is equal to mass (m_A) of soluted substance and volume (V) of the solution proportion. SI unit for mass concentration is kg m^-3, but in laboratory practice g dm^-3, which has the same number value, is often used.

mass spectrometry    →   masena spectrometrija

Mass spectrometry is an analytical technique in which ions are separated according to the mass/charge (m/e) ratio and detected by a suitable detector.

In a mass spectrometer a sample is ionised and the positive ions produced are accelerated into a high-vacuum region containing electric and magnetic fields. These fields deflect and focus the ions onto a detector. A mass spectrum is thus obtained, consisting of a series of peaks of variable intensity to which m/e values can be assigned. Different molecules can be identified by their characteristic pattern of lines.