CHEMISTRY GLOSSARY

iodine    →   jod

Iodine was discovered by Bernard Courtois (France) in 1811. The origin of the name comes from the Greek word iodes meaning violet. It is shiny, black, non-metallic solid with characteristic odour. Sublimes easily and as a gas it is violet and intensely irritating to the eyes, nose and throat. Iodine occurs on land and in the sea in sodium and potassium compounds. Required in small amounts by humans. Once used as an antiseptic, but no longer due to its poisonous nature.

oxime    →   oksim

Oximes are organic compounds of structure R₂C=NOH derived from condensation of aldehydes or ketones with hydroxylamine. Oximes from aldehydes may be called aldoximes; those from ketones may be called ketoximes.

ozonide    →   ozonid

Ozonides are explosive organic compounds, mainly oleaginous foul liquids. They emerge in the process of ozonization from some satiated compounds. They are important for structure determining.

ozonolisys    →   ozonoliza

Ozonolisys is a procedure of adding ozone to an unsaturated organic compound, by which first ozonides emerge, and then degrade.

PCl5 reaction    →   reakcija s PCl5

Reaction with phosphorus pentachloride (PCl₅) is a characteristic of organic compounds containing a hydroxyl group and this reaction is used to identify these compounds in an organic analysis.

percolation    →   perkolacija

Percolation is a procedure of extraction of a material in special pipes through which a solvent is gradually released.

peroxide    →   peroksid

Peroxides are compounds of structure ROOR in which R may be any organic group. In inorganic chemistry, salts of the anion O₂^2-. They are strong oxidising agents.

ketal    →   ketal

Ketals are organic compounds formed by addition of an alcohol to a ketone. If one molecule of ketone (RR’CO) reacts with one molecule of alcohol (R"OH) then a hemiketal is formed. The rings of ketose sugars are hemiketals. Further reaction produces a full ketal (RR’C(OR")₂). This term, once abandoned, has been reinstated as a subclass of acetals.

ketone    →   keton

Ketones are compounds in which a carbonyl group is bonded to two carbon atoms: R₁R₂C=O (neither R may be H). They are derived by oxidation of secondary alcohols. The simplest member of the series is acetone, (CH₃)₂CO.

Kjeldahl’s method    →   Kjeldahlov postupak

Kjeldahl’s method is an analytical method for determination of nitrogen in certain organic compounds. The method was developed by the Danish chemist Johan Kjeldahl (1849-1900).

It involves addition of a small amount of anhydrous potassium sulphate to the test compound, followed by heating the mixture with concentrated sulphuric acid, often with a catalyst such as copper sulphate. As a result ammonia is formed. After alkalyzing the mixture with sodium hydroxyde, the ammonia is separated by distillation, collected in standard acid, and the nitrogen determined by back-titration.

1. Kjeldahl flask for decomposition (500 ml – macro or 100 ml - micro)
2. funnel for alkaline solution
3. Wagner tube (drop catcher)
4. condenser
5. absorption flask with known volume of standard acid