CHEMISTRY GLOSSARY

brass    →   mjed

Brasses are alloys of copper and zinc (generally 5 % to 40 %). Brass has been known to man since prehistoric times, long before zinc itself was discovered. It was produced by melting copper together with calamine, a zinc ore. Its ductility reaches a maximum with about 30 % zinc and its tensile strength with 45 % although this property varies greatly with the mechanical and heat treatment of the alloy. Typical applications included gears, plumbing ware fittings, adapters, valves and screw machine products. The French horn is a valved brass wind instrument.

Brass may contain small amounts of other alloying elements, such as aluminum, lead, tin, or nickel. Lead can be added as an alloying element resulting in a brass that can be rapidly machined and produces minimal tool wear. Additions of aluminium, iron and manganese to brass improve strength, whilst silicon additions improve wear resistance. Brass containing tin (< 2 % ) is less liable to corrosion in seawater; it is sometimes called naval brass and is used in naval construction.

active site    →   aktivno mjesto

Active site is a pocket or crevice on an enzyme molecule that fits reactant molecules like a hand in a glove. The active site lowers the activation energy for reaction

limiting reactant    →   mjerodavni reaktant

Limiting reactant is a reactant in a chemical reaction that limits the amount of product that can be formed. The reaction will stop when the entire limiting reagent is consumed. These other reactants are present in excess.

miscible matter    →   mješljiva tvar

Miscible matter is capable of being mixed in any ratio with another matter without separation of two phases.

absolute error    →   apsolutna pogreška

Absolute error is a difference between the obtained value (O) and the real value (μ). It is shown in employed for measuring (g, cm³, ...). For example, if three replicate weights for an object are 1.00 g, 1.05 g, and 0.95 g, the absolute error can be expressed as ±0.05 g. Absolute error is also used to express inaccuracies; for example, if the "true value" is 1.11 g and the measured value is 1.00 g, the absolute error could be written as 1.00 g - 1.11 g = -0.11 g. Note that when absolute errors are associated with indeterminate errors, they are preceded by "±"; when they are associated with determinate errors, they are preceded by their sign.

absolute temperature    →   apsolutna temperatura

Absolute temperature denoting a temperature measured on the absolute scale, a scale of temperature based on absolute zero as the lowest temperature.

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.

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.

air    →   zrak

Air that we breathe is a mixture of gases. The composition of dry-air at sea level is shown below:

air curtain    →   zračna zavjesa

Air curtain is a constant stream of bubbles provided by a submerged diffuser (usually a tube type), which surrounds a specified area.