Saltwater, electrical circuits

Most people associate the word electricity with wires and the motion of electrons through those wires. Makes sense, because that s the kind of electricity we encounter on a day-to-day basis. In the previous section, though, all of your electrical circuits involved liquids—saltwater, copper sulfate dissolved in water, and vinegar. In each case, ions (charged atoms or molecules) in the liquids moved around instead of electrons. An electric current is defined as any movement of charges, not just the movement of electrons. Because we re dealing with ions in addition to electrons, we call the process electrochemistry. 

Figure 19.13 shows the mechanism of rust formation. The electric circuit is completed by the migration of electrons and ions this is why rusting occurs so rapidly in saltwater. In cold climates, salts (NaCl or CaCN) spread on roadways to melt ice and snow are a major cause of rust formation on automobiles. 

Measure the short-circuit current between the steel and copper. This current measured represents the current that would flow between the two materials if they were in electrical contact with one another in the saltwater environment. 

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