Principle

In a concentration series, the voltage is higher the greater the difference in the concentrations of the solutions in the half-cells. No voltage is measurable with a concentration series consisting of two half-cells which are exactly the same, e.g. copper electrodes in 0.1 molar copper sulphate solution. However, when ions (e.g. iodide ions) are added to one of the half-cells which form a sparingly soluble compound with the effective metal ions in the solution (e.g. Cu2+), then a part of the effective metal ions are lost by precipitation (iodide ions react with Cu2+ to form sparingly soluble copper(I) iodide). The result is the formation of a difference in concentration between the two solutions in the half-cells, whereby the voltage of the concentration series increases.

 

What you can learn about


 Influence of the concentration on the electrochemical potential


 

Benefits


Easy teaching and efficient learning by using interactive experimentation PHYWE-Software

Experiment is part of a complete solution set with experiments for the topic Electrochemistry matched with international curriculum: all topics are covered