thermodynamics in corrosion

MEHRAN UNIVERSITY OF ENGINEERING AND TECHNOLOGY, JAMSHORO, SINDH, PAKISTAN

DEPARTMENT OF METALLURGY AND MATERIALS ENGINEERINGDEPARTMENT OF METALLURGY AND MATERIALS ENGINEERING

A + B C + D

A + B AB C + D

G is negative E is positive.

In electrical and electrochemical processes, electrical work is defined as the product of charges moved (Q) times the potential (E) through which it is moved.

If this work is done in an electrochemical cell in which the potential difference between its two half-cells is E, and the charge is that of one mole of reaction in which n moles of electrons are transferred, then the electrical work (-w) done by the cell must be nE.

In this relationship, the Faraday constant F is required to obtain coulombs from moles of electrons.

In an electrochemical cell at equilibrium, no current flows and the energy change occurring in a reaction is expressed in equation:

∆G is negative E is positive for spontaneous reaction.

Express the standard electrode potential ∆ EO of a metal in terms of Gibbs free energy change ∆GO. Hence calculate the value of ∆GO

at standard temperature and pressure for the corrosion of iron, assuming a divalent reaction.