CHEMISTRY GLOSSARY

work    →   rad

Work is the energy required to move an object against an opposing force. Work is usually expressed as a force times a displacement.

When a constant force F acts on a point-like object while the object moves through a displacement s, the force does work W on the object. If force and displacement are at a constant angle Θ to each other, the work is expressed by the scalar product of these two vectors:

When the force F on a point-like object is not constant that is, it depends on the position of the object, the work done by force while object moves from initial position with coordinates (x_i, y_i, z_i) to final position with coordinates (x_f, y_f, z_f)is given by expression:

Where F_x, F_y and F_z are scalar components of the force.

SI unit for work is joule (J); 1 J = 1 Nm = 1 kg m² s^-2. The electron-volt (eV) is commonly used in atomic and nuclear physics.

Heyrovsky-Ilkovic equation    →   Heyrovsky-Ilkovičeva jednadžba

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. E_1/2 is a unique potential (for a given reaction and supporting electrolyte) termed the half-wave potential.

In order to obtain E_1/2 from the above equation, we plot a graph of ln[(i_d-i)/i] against E. The intercept on the x-axis gives then an accurate value of E_1/2. The slope of the obtained straight line is equal to nF/RT from which n is determined.