Editing Relative density (section)

==Uses==
Relative density can also help to quantify the [[buoyancy]] of a substance in a [[fluid]] or gas, or determine the density of an unknown substance from the known density of another. Relative density is often used by [[geologist]]s and [[Mineralogy|mineralogists]] to help determine the [[mineral]] content of a rock or other sample. [[Gemology|Gemologists]] use it as an aid in the identification of [[gemstone]]s. Water is preferred as the reference because measurements are then easy to carry out in the field (see below for examples of measurement methods).

As the principal use of relative density measurements in industry is determination of the concentrations of substances in aqueous solutions and these are found in tables of RD vs concentration it is extremely important that the analyst enter the table with the correct form of relative density. For example, in the brewing industry, the [[Plato scale|Plato table]], which lists sucrose concentration by mass against true RD, were originally (20&nbsp;°C/4&nbsp;°C)<ref name="ReferenceA"/> that is based on measurements of the density of sucrose solutions made at laboratory temperature (20&nbsp;°C) but referenced to the density of water at 4&nbsp;°C which is very close to the temperature at which water has its maximum density of ''ρ''({{chem|H|2|O}}) equal to 0.999972&nbsp;g/cm<sup>3</sup> (or 62.43&nbsp;lb·ft<sup>−3</sup>). The [[American Society of Brewing Chemists|ASBC]] table<ref name="ReferenceB"/> in use today in North America, while it is derived from the original Plato table is for apparent relative density measurements at (20&nbsp;°C/20&nbsp;°C) on the IPTS-68 scale where the density of water is 0.9982071&nbsp;g/cm<sup>3</sup>. In the sugar, soft drink, honey, fruit juice and related industries sucrose concentration by mass is taken from this work<ref name=briggs>Hough, J.S., Briggs, D.E., Stevens, R and Young, T.W. Malting and Brewing Science, Vol. II Hopped Wort and Beer, Chapman and Hall, London, 1997, p. 881 {{ISBN|0-412-16590-2}}</ref> which uses SG (17.5&nbsp;°C/17.5&nbsp;°C). As a final example, the British RD units are based on reference and sample temperatures of 60&nbsp;°F and are thus (15.56&nbsp;°C/15.56&nbsp;°C).<ref name=briggs/>

Relative density is use in medicine particularly in pharmaceutical field. It is used in [[compounding|automated compounders]] in preparation of multicomponent mixtures for [[parenteral nutrition]], while it is an important factor in [[urinalysis]], relative density is an indicator of both the concentration of particles in the urine and a patient's degree of hydration.<ref>{{cite book |last1=Stockton |first1=Shelly J. |title=Stoklosa and Ansel's Pharmaceutical Calculations |date=2022 |publisher=[[Wolters Kluwer]] |isbn=978-1-9752-0680-2 |page=81 |edition=16|language=en}}</ref>