what is tailing of mercury how is it removed

Tailing of mercury is a surface-chemistry effect where metallic mercury loses its shine and smooth meniscus, then spreads out and sticks to the glass walls of a vessel after reacting with ozone.

Quick Scoop

• When clean liquid mercury is exposed to ozone, it gets slowly oxidized on the surface.
• This forms a thin layer of mercurous oxide, Hg2OHg_2OHg2​O, on the mercury and on the glass walls.
• Because of this oxide film, mercury:
  • Loses its lustre.
  • Loses its clear meniscus.
  • Starts sticking in a “tail-like” film to the glass, instead of forming a round mobile bead.

In textbook language:

“Tailing of mercury” is the phenomenon in which mercury loses its lustre and meniscus and sticks to the walls of a glass vessel due to formation of Hg2OHg_2OHg2​O when mercury reacts with ozone.

Chemical cause

• Reaction with ozone:

2Hg+O3→Hg2O+O22Hg+O_3\rightarrow Hg_2O+O_22Hg+O3​→Hg2​O+O2​

This Hg2OHg_2OHg2​O is the oxide that coats the mercury and glass, causing the tailing.

How tailing of mercury is removed

There are two closely-related ways often mentioned in exam/learning resources (different books stress one or the other):

1. Using hydrogen peroxide ( H2O2H_2O_2H2​O2​)
   • Hydrogen peroxide reduces mercurous oxide back to metallic mercury:

Hg2O+H2O2→2Hg+H2O+O2Hg_2O+H_2O_2\rightarrow 2Hg+H_2O+O_2Hg2​O+H2​O2​→2Hg+H2​O+O2​

 * This regenerates bright, mobile mercury and removes the tailing effect.

 * Many competitive-exam solutions explicitly give:  

“Tailing of mercury is caused by O3O_3O3​ and removed by H2O2H_2O_2H2​O2​.”

2. By shaking with water (alternative description)
   • Some solutions state that shaking mercury with water dissolves or removes the oxide layer Hg2OHg_2OHg2​O from the glass walls and surface, restoring clean mercury.

 * Concept is the same: remove the oxide film so mercury becomes shiny and non-sticky again.

For exam-style Q&A, the safest, most standard line is:

• Cause: Tailing of mercury is caused by reaction of mercury with ozone forming Hg2OHg_2OHg2​O.

• Removal: It is removed by treating with hydrogen peroxide, which converts Hg2OHg_2OHg2​O back to metallic mercury (restoring lustre and meniscus).

Meta description (SEO-style):
Learn what “tailing of mercury” is in chemistry, why mercury loses lustre and sticks to glass after reacting with ozone, and how this effect is removed using hydrogen peroxide in standard textbook explanations.

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