Calculate the emf and △Go for the cell reaction at 25oC:
Zn(s)|Zn2+(aq) ||Cd2+ (aq)| Cd(s)
Zn2+(aq) = (0.1 M)
Cd2+ (aq) = (0.01 m)
Given Eo Zn2+/Zn = -0.763 and Eo Cd2+/Cd = -0.403 V
Define the following terms :
(1) Equivalent conductivity
(2) Corrosion of metals
(1) It is defined as conductivity power of all ions produced by dissolving one gram equivalent of an electrolyte in solution,
(2) When the surface of a metal is attacked by air, water and some other substance, it is said to corrode. The phenomenon is known as corrosion.
When iron is exposed to moist air for a long time, its surface acquires a coating of a brown, flaky substance. The brown surface easily peel off the iron surface, which if exposed further to moist air again acquires more of that brown layer. This is due to corrosion of iron in moist-air. The flaky substance formed is called rusk Rust is mainly hydrated ferric oxide, Fe2O3 · xH2O.
Another example is copper metal. The surface of copper in moist air acquires a green coating of basic copper carbonate, Cu(OH)2 or CuCO3.
The specific conductivity of a solution containing 5 g of anhydrous BaCl2 (mol. wt = 208) in 1000 cm3 of a solution is found to be 0.0058 ohm–1cm–1. Calculate the molar and equivalent conductivity of the solution.
What is an electrochemical series? How is it useful in predicting whether a metal can liberate hydrogen from acid or not?