Electric Pickle
A whole pickle is placed between two metal electrodes and electricity is passed through the pickle. The characteristic color of a sodium vapor lamp is emitted.
A video of this demonstration is available
https://www.youtube.com/watch?v=0ijsRfsilQ4
Lecture slides to accompany this demonstration are available to download from the menu to the right..
The high concentration of sodium chloride in the pickle serves as an electrolyte solution to conduct electricity. Once the variac is turned on, arcing will occur in the pickle and after a short time a yellow-orange glow will be observed at one end of the pickle. This yellow-orange color is a result of a 3p → 3s electron transition in sodium atoms resulting in an emission of energy in the form of visible light. This light emission from a pickle can be compared to a standard sodium flame test or the light from a sodium vapor lamp.
Extension of the demonstration
Abstrract from J. Chem. Educ., 2005, 82 (4), p 545. The electric pickle demonstration has long been used to explore the atomic emission of sodium ions, which emit a brilliant yellow / orange glow. The emission from other metal ions including lithium, potassium, strontium, and barium can also be demonstrated by pickling cucumbers with the corresponding chloride salt. Cucumbers were bleached with hydrogen peroxide, pickled using a 10% salt solution in vinegar, and electrified using a unique device. The pickled cucumbers glowed pink, purple, red, and yellow, respectively. The glowing pickles provided characteristic line spectra when visualized through a diffraction grating. This adaptation of a classic demonstration provides an eye-catching alternative to discharge tubes for classroom discussions of atomic emission and line spectra.
From the electric pickle apparatus, insert electrodes into opposite ends of the pickle. There is a band of yellow tape on the top electrode indicating the correct depth of penetration of the pickle. Make sure the electrodes do not touch each other inside the pickle. Clamp tte lid on the glass tank. closed. Using alligator clips, connect the exposed electrodes . The alligator clips are connected to the power supply (Variac). The demonstrator ensures that the apparatus is not in contact with anyone. The fume fan is turned on, then the Variac is turned on and the voltage slowly increased to 110 V.
Large dill pickle, electric pickle apparatus, lecture demonstration table
