The reader can find in the following notes some of the most common conversion formulas, chemical names and other things we do think are useful to solve those little but often harsh problems which are to be met in chemistry lab work and in Old Techniques field as well.

conversion between Baumé degrees and density

conversion volumes (hydrogen peroxide) - percentage

conversione between Celsius and Fahrenheit

chemical names

NOTE: conversion calculators work both ways. Some browsers need a few seconds to display the results.
For unclear reasons, the calculators do not work with Opera 7.11.






Density as Baumé degrees
The density scale in Baumé degrees is a non-metric scale, still used mostly for tradition's sake. Baumé degrees are often referred to as Bé.

Two Baumé scales exist, one for heavier-than-water (HTW) liquids and one for lighter (LTW) ones.
In the first one zero matches the reading on the densimeter in pure water, and 15 the reading for a 15% solution of sodium chloride.
In the lighter-than-water scale zero matches the reading for a 10% solution of sodium chloride and 10 matches the reading when the densimeter is placed in pure water.
The following relationships exist between Baumè degrees and specific weight:

a) for HTW liquids (i.e. hydrochloric acid, sulfuric acid, nitric acid, Arabic gum)


b) for LTW liquids (i.e. ammonia, alcohol-water solutions)




Volumes Concentration (Hydrogen peroxide)
Because of tradition, Hydrogen peroxide's concentration is often expressed as volumes instead of percentage.
The word volumes means how many gaseous oxygen volumes would be freed from decomposition of one volume of peroxide solution as per the following formula:

Unfortunately there is no linear relationship between volumes and percentage, and it is then necessary to refer to this table, made from data given in http://www.h2o2.com/intro/properties/physical.html (site of a peroxide maker):


So a simple calculus is enough to convert a unit system in the other one at least when dealing with up to 10% solutions, or 34 Volumes (the max concentration commercially usually available through drugstores is 32 volumes, but sometimes also 120 volumes can be found). For the laziest one, the following calculator is at hand!.

Interpolation of data is necessary when dealing with higher concentrations, like in the following example:
Let's say we have a 50 volumes solution and we need knowing its weight/volume percentage.
The value is between 34.3 and 71.19, while the resulting percentage is between 10.3% and 21.6%. The difference between the last two values is 11.3, while the difference between volumes is 71.19-34.03=37.16. The difference between 50 volumes and 34.03 is 15.97.
The following proportion can be used: 37.16:15.97=11.3:x Pertanto, si scrive la seguente proporzione: 37.16 : 15.97 = 11.3 : x
thus x=15.93·11.3/37.16=1.8
The resulting value is then to be added to the lower limit of the corresponding concentration class (10.3). The exact weight to volume concentration for 50 volumes Hyd. peroxide equals 10.3+1.8=12.1.

For the calculator…. we need to wait!





Celsius and Fahrenheit temperature
Temperature in Celsius degrees has been defined setting zero at the ice/water equilibrium temperature and setting 100 at the water/vapor equilibrium temperature, that is when boiling, then dividing this interval in 100 parts.
Since 1948 the zero definition has been slightly modified and now the centigrade scale is named Celsius scale.
The Fahrenheit scale has been initially defined setting zero at the temperature reached by a 50% ice/salt mix (roughly -18°C), 30 at the ice/water equilibrium temperature and 96 at the body temperature. This scale has been modified so that the interval between the ice/water temperature and the boiling water temperature would be divided into 180 parts. To do this, 32 has been set as the ice/water equilibrium temperature and 212 at the water/vapor temperature.

The conversion between Celsius and Fahrenheit degrees is as follows:







Naming of chemicals
Despite of international efforts for a standard naming, in chemistry are still used old names and habits. One can imagine in the old techniques where it is sometimes necessary to browse though papers dated over a century ago...

	sodium tiosulphate	sodium hyposulphite
sodium hydrogencarbonate	sodium bicarbonate	bicarbonate of soda, natron
sodium carbonate	washing soda	sal soda, soda ash
	potassium permanganate	mineral chameleon
	potassium sulphide	liver of sulphur
potassium hexacyanoferrate (III)	potassium ferricyanide	red prussiate
potassium hexacyanoferrate (II)	potassium ferrocyanide	yelow prussiate
mercury chloride (II)	mercuric chloride	corrosive sublimate
copper sulphate (II)	cupric sulphate	blue vitriol
iron sulphate (II)	ferrous sulphate	green vitriol
potassium aluminium sulphate	potassium alum	alum ammon