CHEMISTRY GLOSSARY
positive pole → pozitivni pol
Positive pole is that half-cell in the electrochemical cell which has the most positive electrode potential.
acid → kiselina
Acid is a type of compound that contains hydrogen and dissociates in water to produce positive hydrogen ions. The reaction for an acid HA is commonly written:
In fact, the hydrogen ion (the proton) is solvated, and the complete reaction is:
This definition of acids comes from the Arrhenius theory. Such acids tend to be corrosive substances with a sharp taste, which turn litmus red and produce colour changes with other indicators. They are referred to as protonic acids and are classified into strong acids, which are almost completely dissociated in water, (e.g. sulphuric acid and hydrochloric acid), and weak acids, which are only partially dissociated (e.g. acetic acid and hydrogen sulphide). The strength of an acid depends on the extent to which it dissociates, and is measured by its dissociation constant.
In the Lowry-Brønsted theory of acids and bases (1923), the definition was extended to one in which an acid is a proton donor (a Brønsted acid), and a base is a proton acceptor (a Brønsted base). An important feature of the Lowry-Brønsted concept is that when an acid gives up a proton, a conjugate base is formed that is capable of accepting a proton.
Similarly, every base produces its conjugate acid as a result of accepting a proton.
For example, acetate ion is the conjugate base of acetic acid, and ammonium ion is the conjugate acid of ammonia.
As the acid of a conjugate acid/base pair becomes weaker, its conjugate base becomes stronger and vice versa.
A further extension of the idea of acids and bases was made in the Lewis theory. In this, a G. N. Lewis acid is a compound or atom that can accept a pair of electrons and a Lewis base is one that can donate an electron pair. This definition encompasses "traditional" acid-base reactions, but it also includes reactions that do not involve ions, e.g.
in which NH3 is the base (donor) and BCl3 the acid (acceptor).
Faraday constant → Faradayeva konstanta
Faraday constant (F) is the electric charge of 1 mol of singly charged positive ions.
where NA is Avogadro’s constant (6.022×1023 mol-1) and e is the elementary charge (1.602×10-19 C).
angular velocity → kutna brzina
A point-like object that undergoes circular motion changes its angular position from initial Θi to final Θf, relative to a fixed axis, specified in a coordinate system with an origin that coincides the centre of the circular path of object. The change in its angular position is called angular displacement ΔΘ = Θf - Θi. Also, a rigid body that rotates about a specified rotation axis, changing its angular position from initial Θi to final Θf, undergoes an angular displacement ΔΘ.
The average angular velocity, ωav, is the ratio of the angular displacement and the time interval Δt=tf-ti, in which that displacement occurs.
Θf and Θi are the initial and final angular position, respectively.
The instantaneous angular velocity ω is the limit of the average angular velocity, as Δt is made to approach zero.
ωav and ω are positive for the counterclockwise rotation (in direction of increasing Θ) and negative for the clockwise rotation (in direction of decreasing Θ).
SI unit for angular velocity is s-1.The measure for the angle Θ is radian. The relationship between radians and degrees is:
For example, the angular velocity of the minute hand of a clock is:
ionisation energy → energija ionizacije
Ionisation energy is the minimum energy required to remove an electron from an isolated atom or molecule (in its vibrational ground state) in the gaseous phase.
metallic bond → metalna veza
Metallic bond is a electrostatic attraction binding the positive ions of a solid metal together by means of a "sea" of delocalised valence electrons
Citing this page:
Generalic, Eni. "Pozitivni pol." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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