MATT MEADOWS / SCIENCE PHOTO LIBRARY MATT MEADOWS / SCIENCE PHOTO LIBRARY
Conductivity test. Assorted solutions being tested for electrical conductivity. All the bulbs are connected to batteries (out of frame to the right) and have electrodes placed in the solution. If the solution conducts electricity, a current will flow between the electrodes, and the bulb will light. The solutions are: hydrochloric acid (HCl), sodium hydroxide (NaOH), sodium chloride, or salt (NaCl), and water (H2O). Only the first three of these conduct electricity. Pure water will not allow a current to flow, and the bulb remains off. The conducting solutions are ionic: their molecules split into charged particles (ions) in solution. It is these.
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