CHEMISTRY GLOSSARY

U-tube manometer    →   U-manometar

U-tube manometer contains water or mercury in a U-shaped tube, and is usually used to measure gas pressure. One end of the U tube is exposed to the unknown pressure field (P) and the other end is connected to a reference pressure source (usually atmospheric pressure) (P_ref), shown in the schematic below.

If fluid C is the atmosphere, fluid B is the liquid in the U tube (e.g. water or mercury), and fluid A is a gas, then we can assume that ρB >> ρA, ρC. The pressure contributed by the weight of gas within the U tube can therefore be neglected. The gage pressure of the gas can be approximated by,

visible radiation    →   vidljivo zračenje

Human eye can only see electromagnetic radiation of wavelengths form 400 nm to 760 nm. This narrow part of electromagnetic spectrum is called visible radiation. Visible (white) light is a mixture of light of all kind of colours, it can be separated, with the help of a glass prism, into its component colours - visible light spectrum, and each colour corresponds to a certain area of wavelengths:

volumetric flask    →   odmjerna tikvica

Volumetric flasks are bottles made of glass, in a pear like in shape with long thin necks and flat bottoms. All come with a ground glass stopper for a tight seal. Volume marking is cut in glass with fluoride acid around the neck, so that parallax should be avoided (flask is put in front of the eyes so that one can see only a straight horizontal line). A volumetric flask is calibrated to contain (TC or In) the indicated volume of water at 20 °C when the bottom of the meniscus is adjusted to just rest on the center of the line marked on the neck of the flask. They are used for preparing the exactly known volume of sample solution and standard solutions of reagents. On each flask with volume designation a temperature on which the flask has been calibrated is designated.

wash bottle    →   boca štrcaljka

Plastic wash bottle is a squeeze bottle made of low density polyethylene (LDPE) whose contents can be forced out through a narrow hole at the top by squeezing the bottle.

Glass wash bottle is a bottle fitted with two glass tubes pass through the cap, so that on blowing into one of the tubes a stream of water issuing from the other may be directed upon anything to be washed or rinsed, as a precipitate upon a filter.

water gas    →   vodeni plin

Water gas (blue gas, synthesis gas) is a fuel gas used in industrial synthesis of organic chemicals, and in welding, glassmaking, and other high-temperature industrial applications. Water gas is made by passing steam over a bed of hot coal or coke. It mainly consists of carbon monoxide (CO) and hydrogen (H₂), contaminated with small amounts of CO₂, N₂, CH₄, and O₂.

Wilson’s chamber    →   Wilsonova komora

Wilson’s chamber is used for detection of radioactive radiation. Wilson’s chamber has a glass cylinder filled with air that has been saturated with water vapour. Radioactive radiation in its way ionises molecules of gas which then function as centres on which water vapour condenses into very small drops, thereupon showing Tyndall’s effect, i.e. is they are visible as a bright trail.

zirconium    →   cirkonij

Zirconium was discovered by Martin Heinrich Klaproth (Germany) in 1789. The origin of the name comes from the Arabic word zargun meaning gold colour. It is grey-white, lustrous, corrosion-resistant metal. Exposed surfaces form oxide protective film. Zirconium is found in many minerals such as zircon and baddeleyite. Used in alloys such as zircaloy this is used in nuclear applications since it does not readily absorb neutrons. Also baddeleyite is used in lab crucibles. Used in high-performance pumps and valves. Clear zircon (ZrSiO₄) is a popular gemstone.

CO2 ion selective electrode    →   CO2 ion selektivna elektroda

The carbon dioxide ion selective electrode uses a gas-permeable membrane to separate the sample solution from the electrode internal solution. Dissolved carbon dioxide in the sample solution diffuses through the membrane until an equilibrium is reached between the partial pressure of CO₂ in the sample solution and the CO₂ in the internal filling solution. In any given sample the partial pressure of carbon dioxide will be proportional to the concentration of carbon dioxide. The diffusion across the membrane affects the level of hydrogen ions in the internal filling solution:

The hydrogen level of the internal filling solution is measured by the pH electrode located behind the membrane. The internal filling solution contains a high concentration of sodium bicarbonate (e.g. 0.1 mol/L NaHCO₃) so that the bicarbonate level can be considered constant.

water jet vacuum pump    →   vodena sisaljka

The water jet vacuum pump or vacuum aspirator is one of the most popular devices that produces vacuum in laboratories. The rapid flow of water through the device creates a vacuum in a side-arm that is connected to a vacuum application such a Buchner flask. The water jet vacuum pump creates a vacuum by means of Venturi effect named after the Italian physicist Giovanni Battista Venturi (1746–1822). The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. Water jet pumps are manufactured of glass, plastic or metal, depending on the conditions in which they are used.