CHEMISTRY GLOSSARY

standard mean ocean water    →   standardna prosječna oceanska voda

Standard mean ocean water (SMOW) is a standard sample of pure water of accurately known isotopic composition which is maintained by the International Atomic Energy Agency. It is used for precise calibration of density and isotopic composition measurements.

standardisation    →   standardizacija

Standardisation is a process of determining the exact concentration of secondary standard solution.

Newman’s projection    →   Newmanova projekcija

Newman’s projection is an image which we get when we observe a model of ethane molecule in C-C bond direction.

standard    →   standard

Standards are materials containing a known concentration of an analyte. They provide a reference to determine unknown concentrations or to calibrate analytical instruments.

The accuracy of an analytical measurement is how close a result comes to the true value. Determining the accuracy of a measurement usually requires calibration of the analytical method with a known standard. This is often done with standards of several concentrations to make a calibration or working curve.

A primary standard is a reagent that is extremely pure, stable, has no waters of hydration, and has a high molecular weight.

A secondary standard is a standard that is prepared in the laboratory for a specific analysis. It is usually standardised against a primary standard.

standard deviation    →   standardna devijacija

Standard deviation (σ) is a measure of the dispersion of a set of data from its mean. Standard deviation is a statistical term that measures the amount of variability or dispersion around an average

Suppose there are many measurements of a quantity presumed to be similar, like the size of peas in a pod. If the number of readings for each size were plotted, a bell-shaped curve would probably result, with a few small and large peas and most clustered around the average size. Around two-thirds of all measurements fall in the range spanned by the standard deviation, a measure of the spread.

standard electrode potential    →   standardni elektrodni potencijal

Standard electrode potential (E°) (standard reduction potentials) are defined by measuring the potential relative to a standard hydrogen electrode using 1 mol solution at 25 °C. The convention is to designate the cell so that the oxidised form is written first. For example,

The e.m.f. of this cell is -0.76 V and the standard electrode potential of the Zn²+|Zn half cell is -0.76 V.

standard hydrogen electrode    →   standardna vodikova elektroda

Standard hydrogen electrode is a system in which hydrogen ion and gaseous hydrogen are present in their standard states. The convention is to designate the cell so that the standard hydrogen electrode is written first.

The electrode is used as a reference (of zero) for the values of other standard electrode potentials.

standard atmosphere    →   standardna atmosfera

See Atmosphere

anomer    →   anomer

Anomers are diastereoisomers of cyclic forms of sugars or similar molecules differing in the configuration at the anomeric carbon (C-1 atom of an aldose or the C-2 atom of a 2-ketose). The cyclic forms of carbohydrates can exist in two forms, α- and β- based on the position of the substituent at the anomeric center. Anomer are designated α if the configuration at the anomeric carbon is the same as that at the reference asymmetric carbon in a Fischer projection. If the configuration differs the anomer is designated β. For example, α-D-glucopyranose and β-D-glucopyranose, the two cyclic forms of glucose, are anomers.

atmosphere    →   atmosfera

1. Atmosphere is the column of air which is extending several hundred kilometers above the surface the Earth's surface. The density of this air decreases as you proceed up from the surface. The air in the atmosphere consists of 78 % nitrogen, 21 % oxygen, and 0.9 % argon. The remaining 0.1 % of the atmosphere consists of ozone, water vapor, carbon dioxide, methane, helium, and neon. The atmosphere is divided into different regions. The lowest two layers are the troposphere (the layer closest to the earth) and the stratosphere respectively. These two layers contain more than 99 % of the atmospheric molecules.

2. Standard atmosphere (atm) is an obsolete pressure and stress unit which should be discontinued. It is unit of pressure equal to the air pressure measured at mean sea level.

1 atm = 101 325 Pa

Technical atmosphere (at) is an obsolete MKpS pressure and sttress derived unit.

1 at = 98 066.5 Pa

1 atm = 1.033 227 453 at