What is a "degree Baumé"?

I work at a water park, and our 55 gallon HCl barrels come labeled as having a concentration of 22 degrees Baumé. I would like to know what the conversion factor is from "degrees Baumeé" to Molar? Chad

	Vocabulary
	Baumé scale hydrometer mass percentage specific gravity

The Baumé scale is a measure of a solution's specific gravity, not its concentration. To get the molarity of the HCl, you'll have to convert degrees Baumé to a specific gravity, and then use the specific gravity to look up the concentration of HCl from a table in a handbook. For example, the CRC handbook has tables that relate specific gravities to concentrations for sulfuric acid.

0 degrees Baume 15 degrees Baume

Pure water 15 (w/w)% NaCl

Calibration of a heavier-than-water
hydrometer on the Baumé scale.

The French chemist Antoine Baumé devised the scale for marking hydrometers. For liquids that are heavier than water, 0°Bé marks the water level of the hydrometer placed in pure water, and 15°Bé corresponds to the water level when the scale is placed in a solution that is 15% NaCl by mass. For liquids that are lighter than water, 10°Bé marks the level for pure water and 0°Bé corresponds to a solution that is 10% NaCl by mass.

At 60°F, specific gravity can be calculated from degrees Baumé using the following formulas:

liquids lighter than water:	sp. gr. = 140/(°Bé + 130)
liquids heavier than water:	sp. gr. = 145/(145 - °Bé)

Note that a "new" scale called the Gerlach scale uses 146.78 in the heavier-than-water equation rather than 145.

Although the Baumé scale is almost never mentioned in chemistry courses, tradesmen often use it as a convenient way to check solution concentration. For example, U. S. Grade A honey must have a Baumé reading of at least 42.49°Bé at 60°F. Recipes for lowering the pH of pool water call for 20°Bé hydrochloric acid. It's also used by brewers for checking the density of sugar solutions before fermentation.

References

[an error occurred while processing this directive]

Author: Fred Senese senese@antoine.frostburg.edu

General Chemistry Online! What is a "degree Baumé"?