Related Experiment Video
Updated: Jun 28, 2026

Characterizing Lewis Pairs Using Titration Coupled with In Situ Infrared Spectroscopy
Published on: February 20, 2020
Ion-pair extraction of Co(II) by crown ethers from perchlorate medium
S M Khalifa1, H F Aly, J D Navratil
1Hot Laboratory Centre, Atomic Energy Authority, 13759 Cairo, Egypt.
Abstract:
The extraction of cobalt(II) by chloroform solutions of the crown ethers (CE) 12C4, I5C5, 18C6, Dbl8C6, Dchl8C6 or Dch24C8 from aqueous perchlorate medium was investigated. Slope analysis of the experimental data suggested that the extraction of Co(II) by these CEs takes place through ion-pair formation, and that the chemical formula of the main extracted species is Co(OH)(+)ClO(-)(4).CE. The magnitudes of the extraction constants are in the sequence 18C6 > Dch18C6 > Dch24C8 > Db18C6 > 15C5 > 12C4, which is discussed in terms of the correspondence between the CE cavity size and the ionic radius of cobalt(II).
Related Concept Videos
Crown Ethers
Extraction: Advanced Methods
Ion Exchange
Precipitation and Co-precipitation
Ion-Exchange Chromatography
Precipitation of Ions
The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:

