23. Solving a chemistry problem

23. Solving a chemistry problem

7. If a drop of water is applied to a steel object, then the middle, and not the outer, part of the wetted metal is corroded. After the drop dries, a rust spot appears in its center. How can this be explained? What part of the metal under the drop of water is the anode and which is the cathode? Make up the electronic equations of the corresponding processes.

Additional information:

If you do not open the file - install the RAR archiver. Inside the archive you will find a solution in Word format.