CHEMISTRY GLOSSARY

gasohol    →   gasohol

Gasohol (E10) is an alternative fuel consisting of a mixture of typically 90 % gasoline with 10 % anhydrous ethanol. It can be used in the internal combustion engines of most modern automobiles and light-duty vehicles without need for any modification on the engine or fuel system.

carboxylic acids    →   karboksilne kiseline

Carboxylic acids are organic compounds characterized by the presence of one or more RC(=O)OH groups (the carboxyl group). In the systematic chemical nomenclature carboxylic acids names end in the suffix -oic (e.g. ethanoic acids, CH₃COOH). The carbon of the terminal group being counted as part of the chain. They are generally weak acids. Carboxylic acids include a large and important class of fatty acids and may be either saturated or unsaturated. There are also some natural aromatic carboxylic acids (benzoic, salicylic).

chemical change    →   kemijska promjena

Chemical change is a process which results in the production of one or more new materials. The system within which the process takes place is called a chemical system. A chemical change is also known as a chemical reaction, where one substance is converted into one or more different substances. When sodium and chlorine react to produce sodium chloride, a chemical reaction has taken place.

chromium    →   krom

Chromium was discovered by Louis-Nicholas Vauquelin (France) in 1797. The origin of the name comes from the Greek word chroma meaning colour. It is very hard, crystalline, steel-grey metal. The pure metal has a blue-white colour. It is hard, brittle and corrosion-resistant at normal temperatures. Hexavalent compounds toxic by skin contact. The most important chromium mineral is chromite [Fe,Mg(CrO₄)]. Produced commercially by heating its ore in the presence of silicon or aluminium. Used to make stainless steel. It gives the colour to rubies and emeralds. Iron-nickel-chromium alloys in various percentages yield an incredible variety of the most important metals in modern technology.

colloid    →   koloid

Colloids are systems in which there are two or more phases, with one (the dispersed phase) distributed in the other (the continuous phase). Moreover, at least one of the phases has small dimensions, in the range between 1 nm and 1 μm (10^-9 m – 10^-6 m). Dimension, rather than the nature of the material, is characteristic. In this size range, the surface area of the particle is large with respect to its volume so that unusual phenomena occur, e.g., the particles do not settle out of the suspension by gravity and are small enough to pass through filter membranes. Macromolecules (proteins and other high polymers) are at the lower limit of this range; the upper limit is usually taken to be the point at which the particles can be resolved in an optical microscope.

Colloidal particles may be gaseous, liquid, or solid, and occur in various types of suspensions:

Sols - dispersions of small solid particles in a liquid.

Emulsions - colloidal systems in which the dispersed and continuous phases are both liquids.

Gels - colloids in which both dispersed and continuous phases have a three-dimensional network throughout the material.

Aerosols - colloidal dispersions of liquid or solid particles in a gas.

Foams - dispersions of gases in liquids or solids.

glacial acetic acid    →   ledena octena kiselina

Glacial acetic acid (CH₃COOH) is the pure compound, as distinguished from the usual water solutions known as acetic acid. It is a colorless liquid or crystalline substance (melting point 16.6 °C) with a pungent, vinegar odor.

condensation    →   kondenzacija

1. Condensation is a process of changing from a gaseous to a liquid or solid state, usually done by cooling.

2. Condensation, in colloid systems, is a process where smaller particle join in one colloid size particle

3. Condensation, in chemical terms, is a sort of chemical reaction in which small molecules like water, carbon dioxide, or ammonia single out.

critical point    →   kritična točka

In general, critical point is the point on the phase diagram of a two-phase system at which the two coexisting phases have identical properties and therefore represent a single phase. At the liquid-gas critical point of a pure substance, the distinction between liquid and gas vanishes, and the vapour pressure curve ends. The coordinates of this point are called the critical temperature and critical pressure. Above the critical temperature it is not possible to liquefy the substance.

degree    →   stupanj

1. Degree is a unit of temperature on a specified scale. The temperatures of boiling and freezing water are: in the Fahrenheit system 212 and 32 degrees; in the Celsius system 100 and 0 (zero) degrees.

2. Degree is a unit of angular measure. A circle is divided into 360 degrees, represented by the symbol °. Degrees are each divided into 60 minutes. Each minute has 60 seconds. Symbols for degree, minute, and second for plane angle is placed after the numerical value and a no space between the numerical value and the unit symbol (α = 2°3'4").

3. In algebra, the degree of a polynomial is the highest power of the variable in the polynomial. For example, 4x³ + 3x² + x + 7 have degree 3.

hardening    →   stvrdnjavanje

Hardening is the process of becoming hard or solid by cooling, or drying, or crystallization. For example, the hardening of concrete.