A chemical substance is an element , a compound or a mixture with certain chemical and physical properties . Chemical substances are also generally referred to as substances , materials (in technology) or matter (in physics).
Definitions in chemistry
In chemistry, substances are divided into
Important basic substances in chemistry are z. B. Water , table salt ( sodium chloride ), iron and alcohol ( ethanol ); important mixtures of substances, e.g. air , hydrochloric acid and potassium hydroxide .
A reaction scheme can be specified for the conversion of a substance into one or more other substances (a chemical reaction ) . In chemistry, the existence of substances is proven by means of detection reactions. Concrete, qualitative detection reactions - especially those from qualitative inorganic chemistry , i.e. for anions and cations - are clearly and methodically described here. The determination of the amount is carried out with the help of modern instrumental analysis methods ( instrumental analysis ).
All fabrics are of a regular nature. If substances consist of the smallest particles, they are atoms or molecules or their ions , otherwise aggregated systems such as clusters or “giant molecules” or formula units . Chemical substances are characterized by their physical properties such as density , melting point or electrical conductivity .
Definitions of the legislator
|Definition of terms in hazardous substances law|
|EU labeling of hazardous substances||"Substance"
use permitted until December 1st, 2012
use allowed until June 1st, 2015
|GHS hazard labeling||"Material"||"Mixture"|
|Swiss Chemicals Ordinance||"Material"||"Preparation"|
|Comprises by chemical definition||Basic substances
(homogeneous and heterogeneous)
Deviating from the above definitions for substances and mixtures that are customary in chemistry, the EU distinguishes between "substances" (these are the pure substances of the above definition, i.e. elements and compounds) and the "preparations" consisting of several substances in the case of EU hazardous substance labeling The GHS labeling can now be referred to as “mixtures”: The legislator only uses substances for what is declared in the scheme as “pure substance” (element or compound) and not as a generic term for everything. Conversely, the terms mixture or preparation do not denote a subset of substance, but are parallel terms. Since the introduction of the GHS, a different date (December 1, 2012) has applied to “substances” than to “preparations” (then “mixtures”, June 1, 2015); such a distinction would not be possible with the definition given at the beginning of the article.
Classification of chemical substances
|Schematic classification of the substances|
Different distinctions of substances (selection)
- Hazardous substances are substances that can represent particular sources of danger, for example with the properties flammable , explosive or toxic .
- As chemical substances which have in the chemistry lab or in the chemical industry are used or produced.
- (Public) substance information system IGS of the state of North Rhine-Westphalia
- Joint substance data pool of the federal and state governments (GSBL)