Chemistry in Pictures: Silver snake

As part of the lectures he gives undergraduates at the University of Illinois Springfield, Harshavardhan Bapat likes to trot out this classic demonstration: the displacement of copper metal by silver ions. At first, when Bapat placed a coil of copper wire into a solution of silver nitrate, it seemed like nothing was happening. But after about 10 min, this mane of silver crystals formed as the silver ions in solution and the copper atoms in the wire started switching places. Specifically, silver ions pick up electrons from the copper, and the copper atoms in turn become soluble ions and impart a blue color to the solution. The demo teaches students about the activity series of metals, a ranked order of metals that reflects which ions can displace which metals. But Bapat likes the demo because it shows students that some chemical reactions don’t happen all at once; they take time to go to completion.

Photo taken and submitted by Harshavardhan Bapat

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