Zinc was discovered by Andreas Marggraf (Germany) in 1746. The origin of the name comes from the German word zink. It is bluish-silver, ductile metal. Reacts with alkalis and acids. Tarnishes in air. Zinc is found in the minerals zinc blende (sphalerite) (ZnS), calamine, franklinite, smithsonite (ZnCO3), willemite and zincite (ZnO). Used to coat other metal (galvanizing) to protect them from rusting. Although some 90 % of the zinc is used for galvanizing steel. Zinc metal is used in the common dry-cell battery. Also used in alloys such as brass, bronze. Zinc compounds are also used in the manufacture of paints, cosmetics, plastics, electronic devices, and other products.
The relationship between the temperature (T) and the salinity (S) of a seawater can be illustrated graphically on a T-S diagram, which is a simple, but powerful tool used in studies of seawater density, mixing, and circulation. In a T-S diagram, temperature is plotted along the vertical axis in degrees Celsius and salinity is measured along the horizontal axis in PSU (Practical Salinity Units). Seawater density is illustrated in the diagram by curved lines of constant density (isopycnals). Water tends to move horizontally throughout the deep ocean, moving along lines of equal density.
The Heyrovsky-Ilkovic equation describes the entire current-potential curve (polarographic wave) of a reversible redox system in polarography
where R is the gas constant, T is the absolute temperature, F is the Faraday constant, n denotes the number of electrons taking part in the electrode reaction. E1/2 is a unique potential (for a given reaction and supporting electrolyte) termed the half-wave potential.
In order to obtain E1/2 from the above equation, we plot a graph of ln[(id-i)/i] against E. The intercept on the x-axis gives then an accurate value of E1/2. The slope of the obtained straight line is equal to nF/RT from which n is determined.
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.
The Lennard-Jones potential (or 12-6 potential) is a mathematically simple model that describes the interaction between two non-bonded and uncharged atoms (known as the van der Waals interaction). It was first proposed in 1924 by British physicist Sir John Edward Lennard-Jones (1894-1954). The Lennard-Jones Potential is given by the following equation
V(r) = 4e[(sigma/r)12-(sigma/r)6)]where V is the intermolecular potential between the two atoms or molecules, ε is the well depth and a measure of how strongly the two particles attract each other, σ is the distance at which the intermolecular potential between the two particles is zero, r is the distance of separation between centres of both particles.
Generalic, Eni. "How many oz in a gram." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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