CHEMISTRY GLOSSARY

parchment paper    →   pergamentni papir

Parchment paper is impermeable paper obtained by dipping cellulosic paper in the sulphuric acid.

litmus paper    →   lakmus-papir

Litmus paper is an unsized paper treated with litmus for the use as an acid-base indicator, in an acid it turns red, and in a base it turns blue.

paper    →   papir

Paper is the thin sheet of material made of cellulose pulp, derived mainly from wood, but also from rags and certain grasses, and processed into flexible leaves or rolls. It is manufactured by bleaching raw material using the bleaching-powder, mixing it with inorganic fillers, colours and glues, and drying. Used primarily for writing, printing, drawing, wrapping, and covering walls.

wrinkled filter paper    →   nabrani filtar-papir

Wrinkled filter paper is a filter made of wrinkled filter paper, by which, due to enlarged surface, fast filtering is achieved.

filter paper    →   filtar papir

Filter paper is a quantitative paper used for filtering and made of pure cellulose treated with hydrochloric and hydrofluoric acid. This kind of paper burns out practically without any remains (less than 0.0001 g ashes). Different types of paper are marked with numbers; qualitative bears marking 595 or 597 and quantitative 589 or 590. Dependable upon precipitate character, different types of filter paper are used:

• black band (589¹) - 100 mL of fluid flows through it in 20 s to 30 s. It is used for filtering of gelatinous precipitates.
• white band (589²) - 100 mL of fluid flows through it in 40 s to 60 s. It is used for coarse crystalline precipitates filtration.
• blue band (589³) - 100 mL of fluid flows through it in 200 s to 400 s. It is used for fine crystalline precipitates.

paper chromatography    →   papirna kromatografija

Paper chromatography is one of the types of chromatography procedures which runs on a piece of specialized paper. It is a planar chromatography systems wherein a cellulose filter paper acts as a stationary phase on which separation of compounds occurs. The edge of the paper is immersed in a solvent, and the solvent moves up the paper by capillary action.

acid    →   kiselina

Acid is a type of compound that contains hydrogen and dissociates in water to produce positive hydrogen ions. The reaction for an acid HA is commonly written:

In fact, the hydrogen ion (the proton) is solvated, and the complete reaction is:

This definition of acids comes from the Arrhenius theory. Such acids tend to be corrosive substances with a sharp taste, which turn litmus red and produce colour changes with other indicators. They are referred to as protonic acids and are classified into strong acids, which are almost completely dissociated in water, (e.g. sulphuric acid and hydrochloric acid), and weak acids, which are only partially dissociated (e.g. acetic acid and hydrogen sulphide). The strength of an acid depends on the extent to which it dissociates, and is measured by its dissociation constant.

In the Lowry-Brønsted theory of acids and bases (1923), the definition was extended to one in which an acid is a proton donor (a Brønsted acid), and a base is a proton acceptor (a Brønsted base). An important feature of the Lowry-Brønsted concept is that when an acid gives up a proton, a conjugate base is formed that is capable of accepting a proton.

Similarly, every base produces its conjugate acid as a result of accepting a proton.

For example, acetate ion is the conjugate base of acetic acid, and ammonium ion is the conjugate acid of ammonia.

As the acid of a conjugate acid/base pair becomes weaker, its conjugate base becomes stronger and vice versa.

A further extension of the idea of acids and bases was made in the Lewis theory. In this, a G. N. Lewis acid is a compound or atom that can accept a pair of electrons and a Lewis base is one that can donate an electron pair. This definition encompasses "traditional" acid-base reactions, but it also includes reactions that do not involve ions, e.g.

in which NH₃ is the base (donor) and BCl₃ the acid (acceptor).

filter    →   filtar

Filter is a device for separating solid particles from a liquid or a gas. The simplest laboratory filter for liquids is a funnel in which a cone of paper (filter paper) is placed. Special containers with a porous base of sintered glass are also used.

neutral substance    →   neutralna tvar

Neutral substance is a substance that shows no acid or base properties, has an equal number of hydrogen and hydroxyl ions and does not change the colour of litmus-paper.

bag filter    →   vrećasti filtar

Bag filter is a unit within a mechanical system that bellows in a bag form when air flows through, cleaning the air by collecting particles of foreign matter. This system of filtering is rated the most efficient- in a range of 92 % to 95 %. Vacuum cleaner have a cloth filter bag.

Bag filter system is an economical method of liquid filtration consisting of the pressure vessel, restrainer basket and micron rated filter bag. Liquid flow is from the inside to the outside of the bag - dirt is trapped inside the bag.