Hydrogen Chloride, HCl

HCl is a very simple example for demonstrating how molecules absorb radiation. Because Cl is much more electronegative than H, HCl has a dipole moment. When HCl vibrates this dipole moment (think of it as an electric field) oscillates. Recall that light is often described as an oscillating electromagnetic field. If the oscillating electric field from some light is at the same frequency as the oscillating electric field from the dipole of the molecule they will be in resonance. Just like when you turn your Harmon Kardon up really loud to listen to Wagner and the windows rattle.

Below is the IR spectrum of HCl.

HCl Infrared Spectrum

Animation of HCl vibration (200k).
HCl spectrum (*.jdx).

This page is maintained by
Scott Van Bramer
Department of Chemistry
Widener University
Chester, PA 19013

Please send any comments, corrections, or suggestions to svanbram@science.widener.edu.

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Last Updated 1/5/96