Heavy liquid

This article is about chemicals. For the music album, see Heavy Liquid (album). For comics, see Heavy Liquid (comics).

A heavy liquid is a solution or liquid chemical substance with a high density and a relatively low viscosity. Heavy liquids are often used for determination of density in mineralogy, for density gradient centrifugation and for separating mixtures.

A bottle of bromoform, a heavy liquid

Uses

Common applications of heavy liquids include:

• Density gradient centrifugation
• Separating mixtures and sink/swim analysis
• Flotation process
• Determination of density

Toxicity

The classical heavy liquids like 1,1,2,2-tetrabromoethane (Muthmanns solution), potassium tetraiodomercurate(II) (Thoulets solution), bromoform or diiodomethane which are used in mineralogy are very toxic. These toxic chemicals are avoided today in consideration of the fact that there are alternative water based, non-toxic heavy liquids like sodium polytungstate solutions.^[1] With this relatively new heavy liquid densities up to 3.1 g·cm⁻³ can be adjusted . Adding parts of pulverulent tungsten carbide increases the density to 4.6 g·cm⁻³.^[2]

List of common heavy liquids with density > 2.0 g·cm−3

Name	Density (g·cm−3)
1,2-Dibromoethane	2.180
cis-1,2-Dibromoethene	2.246
trans-1,2-Dibromoethene	2.231
Dibromomethane	2.477
Bromal	2.550
Bromoform	2.890
1,1,2,2-Tetrabromoethane (Muthmanns solution)	2.967
Sodium polytungstate	3.100
Bromine	3.1028
Thoulets solution	3.196
Diiodomethane	3.325
Indium(III) iodide	3.40[3]
Barium tetraiodomercurate(II)	3.57
Thallium formate + thallium malonate (Clerici solution)	4.25
Galinstan (gallium, indium, tin alloy)	6.44
Mercury	13.6

Mercury is the heaviest liquid at room temperature. But the heaviest liquid irrespective of temperature is liquid osmium (a rare metal) at its melting point (3033°C/5491.4°F), with a density of 22.59 g·cm⁻³, 1.65 times as heavy as mercury.^[4]