42 Rates

Density Measurement Applications

The density of liquids is an important physical parameter that plays a critical role not only in consumer protection, trade, safety and healthcare, taxation, and environmental protection but also in research and development.

Accurate density measurement is key for characterizing oils and fuels, for example, as well as determining alcohol concentration in alcoholic beverages for fiscal purposes or sugar content in non-alcoholic beverages.

It’s also essential for quantifying large amounts of liquid goods when converting a mass flow into a volume flow or vice versa.^[1]

Density-based concentration determination

One of the most important applications of density measurement is determining the concentration of binary solutions (i.e., mixtures of two components, such as alcohol-water solutions or sugar/water solutions).

The density of a solution depends on the concentration of the dissolved substance (“solute”); if the interrelationship is known, the density can be measured and then converted into the respective concentration. A typical application is the determination of sugar content in the soft drink industry. By determining the density of a soft drink, which is considered a sugar-water solution, you can also determine its sugar content.

Concentration determination is also possible when a mixture contains several components and only one of them varies while all other ingredients are constant.

Modern digital density meters today often include numerous chemical concentration tables for the most important industrial compounds, such as those below.

Acids

Name	Conc. Range (% w/w)	Accuracy Approx. (%) ^Δ
acetic acid (CH₃COOH)	0–60	0.09
citric acid anhydr. (C₆H₈O₇)	0–30	0.02
citric acid hydr. (C₆H₈O₇·H₂O)	0–30.6	0.02
EDTA anhydr. (C₁₀H₁₆N₂O₈)	0–6	0.02
EDTA hydr. (C₁₀H₁₆N₂O₈·2H₂O)	0–6.64	0.02
formic acid (CH₂O₂)	0–70	0.04
hydrochloric acid (HCl) *	0–40	0.02
lactic acid (C₃H₆O₃)	0–80	0.04
malic acid (C₄H₆O₅)	0–70.1	0.02
nitric acid (HNO₃)	0–100	0.07
oxalic acid (C₂H₂O₄)	0–8	0.02
phosphoric acid (H₃PO₄)	0–100	0.06
sulfuric acid (H₂SO₄)	0–93	0.05
tartaric acid (C₄H₆O₆)	0–58	0.02
trichloroacetic acid (C₂HCl₃O₂)	0–50	0.02

* Not available for Combined Density and Sound Velocity Meters
Δ The specified accuracy is based on the underlying literature tables

Concentration of different aqueous acids in mol/L according to different tables, based on true density at 20 °C:

Name	Conc. Range (mol/L)
hydrochloric acid (HCl)	0-13.1
nitric acid (HNO₃)	0-24
sodium hydroxide (NaOH)	0-19.07
phosphoric acid (H₃PO₄)	0-19.07
sulfuric acid (H₂SO₄)	0-17.6

Bases

Concentration of different aqueous bases in percentage by weight (% w/w) according to different tables, based on true density at 20 °C:

Name	Conc. Range (% w/w)	Accuracy Approx. (%) ^Δ
ammonia (NH₃)	0–30	0.03
ammonium hydroxide (NH₄OH)	0–61.74	0.06
potassium hydroxide (KOH)	0–50	0.01
sodium hydroxide (NaOH)	0–50	0.04

Δ The specified accuracy is based on the underlying literature tables

Alcohols

Concentration of different aqueous alcohols in percentage by weight (% w/w) according to different tables, based on true density at 20 °C:

Name	Conc. Range (% w/w)	Accuracy Approx. (%) ^Δ
ethylene glycol (C₂H₆O₂)	0–60	0.08
glycerol (C₃H₈O₃)	0–100	0.04
methanol (CH₃OH)	0–100	0.05
1-propanol (C₃H₈O)	0–100	0.05
2-propanol (C₃H₈O)	0–100	0.05
propylene glycol (C₃H₈O₂)	0–60	0.14

Δ The specified accuracy is based on the underlying literature tables

Ethanol

Ethanol concentrations in percentage by volume (% v/v) or percentage by weight (% w/w) according to ethanol concentrations tables issued by different organizations/authors:

Name	Description
ethanol Canadian excise (% v/v)	Special ethanol table converting the output of a special adjustment into an ethanol value
ethanol AOAC 60 °F (% v/v)	Percentage by volume at 15.56 °C (60 °F), American Organization of Analytical Chemists (AOAC) tables, based on true density at 20 °C. The measuring temperature has to be 20 °C (68 °F).
ethanol AOAC 60 °F (% v/v) (not visc.-corr.)	Percentage by volume at 15.56 °C (60 °F), American Organization of Analytical Chemists (AOAC) tables, based on true density at 20 °C. The measuring temperature has to be 20 °C (68 °F), without viscosity correction.
ethanol HM C&E (% v/v)	HM C&E table at 20 °C
ethanol HM C&E (% w/w)	HM C&E table at 20 °C
ethanol IUPAC (% v/v)	Tables of the International Union of Pure and Applied Chemistry (IUPAC), based on true density at 20 °C. The measuring temperature has to be 20 °C (68 °F).
ethanol IUPAC (% w/w)	Tables of the International Union of Pure and Applied Chemistry (IUPAC), based on true density at 20 °C. The measuring temperature has to be 20 °C (68 °F).
ethanol Kaempf (% v/v)	Percentage by volume according to W. Kaempf, based on true density at 20 °C
ethanol Kaempf (% w/w)	Percentage by weight according to W. Kaempf, based on true density at 20 °C
ethanol OIML (% v/v)	According to the tables of the International Organization of Legal Metrology (OIML), temperature according to ITS 68, based on true density at 20 °C
ethanol OIML (% w/w)	According to the tables of the International Organization of Legal Metrology (OIML), temperature according to ITS 68, based on true density at 20 °C
SHUSEI-DO (% v/v)	Percentage by volume at 15 °C (59 °F), based on true density at 15 °C (59 °F). The measuring temperature has to be 15 °C (59 °F).
ethanol OIML-ITS-90 (% v/v)	According to the tables of the International Organization of Legal Metrology (OIML), temperature according to ITS 90, based on true density at 20 °C
ethanol OIML-ITS-90 (% w/w)	According to the tables of the International Organization of Legal Metrology (OIML), temperature according to ITS 90, based on true density at 20 °C
ethanol Proof 60 °F (EtOH °Proof)	Proof degrees at 15.56 °C (60 °F), based on true density at 20 °C
ethanol Proof 60 °F (EtOH °Proof) (not visc.-corr.)	Proof degrees at 15.56 °C (60 °F), based on true density at 20 °C, without viscosity correction

Inorganic salts

Concentration of different inorganic salts in percentage by weight (% w/w) according to different tables, based on true density at 20 °C:

Name	Conc. Range (% w/w)	Accuracy Approx. (%) ^Δ
ammonium chloride (NH₄Cl)	0–24	0.03
ammonium sulfate ((NH₄)₂SO₄)	0–40	0.02
barium chloride anhydr. (BaCl₂)	0–26	0.01
barium chloride hydr. (BaCl₂·2H₂O)	0–30	0.01
cadmium chloride (CdCl₂)	0–56	0.01
cadmium sulfate (CdSO₄)	0–40	0.01
calcium chloride anhydr. (CaCl₂)	0–40	0.01
calcium chloride hydr. (CaCl₂·H₂O)	0–52.99	0.01
cesium chloride (CsCl)	0–64	0.01
cobaltous chloride anhydr. (CoCl₂)	0–20	0.01
cobaltous chloride hydr. (CoCl₂·6H₂O)	0–36.6	0.02
cupric sulfate anhydr. (CuSO₄)	0–18	0.01
cupric sulfate hydr. (CuSO₄·5H₂O)	0–28.16	0.01
dipotassium phosphate anhydr. (K₂HPO₄)	0–8	0.01
dipotassium phosphate hydr. (K₂HPO₄·3H₂O)	0–10.48	0.02
disodium phosphate anhydr. (Na₂HPO₄)	0–5.5	0.01
disodium phosphate hydr. (Na₂HPO₄·7H₂O)	0–10.39	0.02
ferric chloride anhydr. (FeCl₃)	0–40	0.01
ferric chloride hydr. (FeCl₃·6H₂O)	0–66.66	0.02
lanthanum nitrate anhydr. (La(NO₃)₃)	0–44	0.01
lanthanum nitrate hydr. (La(NO₃)₃·6H₂O)	0–58.64	0.01
lithium chloride (LiCl)	0–30	0.02
magnesium chloride anhydr. (MgCl₂)	0–30	0.01
magnesium chloride hydr. (MgCl₂·6H₂O)	0–64	0.02
magnesium sulfate anhydr. (MgSO₄)	0–26	0.01
magnesium sulfate hydr. (MgSO₄·7H₂O)	0–53.24	0.02
manganous sulfate anhydr. (MnSO₄)	0–20	0.01
manganous sulfate hydr. (MnSO₄·H₂O)	0–22.39	0.01
monopotassium phosphate (KH₂PO₄)	0–10	0.01
monosodium phosphate anhydr. (NaH₂PO₄)	0–40	0.01
monosodium phosphate hydr. (NaH₂PO₄·H₂O)	0–46	0.01
nickel sulfate anhydr. (NiSO₄)	0–6	0.01
nickel sulfate hydr. (NiSO₄·6H₂O)	0–10.29	0.02
potassium bicarbonate (KHCO₃)	0–24	0.01
potassium biphthalate (C₈H₅KO₄)	0–8	0.02
potassium bromide (KBr)	0–40	0.01
potassium carbonate anhydr. (K₂CO₃)	0–50	0.01
potassium carbonate hydr. (K₂CO₃·1½H₂O)	0–59.78	0.01
potassium chloride (KCl)	0–24	0.01
potassium chromate (K₂CrO₄)	0–30	0.01
potassium dichromate (K₂Cr₂O₇)	0–10	0.01
potassium ferricyanide anhydr. (K₃Fe(CN)₆)	0–30	0.02
potassium ferrocyanide anhydr. (K₄Fe(CN)₆)	0–20	0.01
potassium ferrocyanide hydr. (K₄Fe(CN)₆·3H₂O)	0–22.93	0.02
potassium iodide (KI)	0–40	0.01
potassium nitrate (KNO₃)	0–24	0.01
potassium oxalate anhydr. (K₂C₂O₄)	0–14	0.01
potassium oxalate hydr. (K₂C₂O₄·H₂O)	0–15.52	0.01
potassium permanganate (KMnO₄)	0–6	0.01
potassium sulfate (K₂SO₄)	0–10	0.01
potassium thiocyanate (KSCN)	0–64	0.02
silver nitrate (AgNO₃)	0–40	0.01
sodium acetate (CH₃COONa)	0–30	0.02
sodium bicarbonate (NaHCO₃)	0–6	0.01
sodium bromide (NaBr)	0–40	0.01
sodium carbonate anhydr. (Na₂CO₃)	0–15	0.01
sodium carbonate hydr. (Na₂CO₃·10H₂O)	0–40.49	0.03
sodium chloride (NaCl)	0–26	0.01
sodium citrate anhydr. (Na₃C₆H₅O₇)	0–36	0.01
sodium citrate hydr. (Na₃C₆H₅O₇·2H₂O)	0–41.03	0.01
sodium dichromate anhydr. (Na₂Cr₂O₇)	0–60	0.01
sodium dichromate hydr. (Na₂Cr₂O₇·2H₂O)	0–68.25	0.01
sodium ferrocyanide anhydr. (Na₄Fe(CN)₆)	0–15	0.01
sodium ferrocyanide hydr. (Na₄Fe(CN)₆·10H₂O)	0–23.89	0.02
sodium molybdate anhydr. (Na₂MoO₄)	0–9	0.01
sodium molybdate hydr. (Na₂MoO₄·2H₂O)	0–10.58	0.01
sodium nitrate (NaNO₃)	0–40	0.01
sodium sulfate anhydr. (Na₂SO₄)	0–22	0.01
sodium sulfate hydr. (Na₂SO₄·10H₂O)	0–49.9	0.02
sodium tartrate anhydr. (C₄H₄Na₂O₆)	0–28	0.01
sodium tartrate hydr. (C₄H₄Na₂O₆·2H₂O)	0–33.2	0.02
sodium thiocyanate (NaCNS)	0–56	0.02
sodium thiosulfate anhydr. (Na₂S₂O₃)	0–40	0.01
sodium thiosulfate hydr. (Na₂S₂O₃·5H₂O)	0–62.79	0.02
sodium tungstate anhydr. (Na₂WO₄)	0–9	0.01
sodium tungstate hydr. (Na₂WO₄·2H₂O)	0–10.1	0.01
strontium chloride anhydr. (SrCl₂)	0–36	0.01
strontium chloride hydr. (SrCl₂·6H₂O)	0–60.55	0.01
trisodium phosphate anhydr. (Na₃PO₄)	0–8	0.01
trisodium phosphate hydr. (Na₃PO₄·12H₂O)	0–18.55	0.02
zinc sulfate anhydr. (ZnSO₄)	0–16	0.01
zinc sulfate hydr. (ZnSO₄·7H₂O)	0–28.5	0.02

Δ The specified accuracy is based on the underlying literature tables

Others

Concentration of various aqueous solutions in percentage by weight (% w/w) according to different tables, based on true density at 20 °C:

Name	Conc. Range (% w/w)	Accuracy Approx. (%) ^Δ
acetone (C₃H₆O)	0–10	0.08
creatinine (C₄H₇N₃O)	0–8	0.04
deuterium oxide (D₂O)	0–100	0.09
1,4-dioxane (C₄H₈O₂)	0–60	0.16
hydrogen peroxide (H₂O₂)	0–100	0.02
procaine hydrochloride (C₁₃H₂₁N₂O₂·HCl)	0–60	0.05
sodium diatrizoate (C₁₁H₈I₃N₂NaO₄)	0–40	0.01
tetracaine hydrochloride (C₁₅H₂₄N₂O₂·HCl)	0–12	0.08
THAM (C₄H₁₁NO₃)	0–40	0.04
urea (NH₂CONH₂)	0–46	0.03

Δ The specified accuracy is based on the underlying literature tables

Extract / sugars

Concentration of different aqueous saccharides and sugar alcohols in percentage by weight (% w/w) according to different tables, based on true density at 20 °C:

Name	Conc. Range (% w/w)	Accuracy Approx. (%) ^Δ
dextrane (C₆H₁₀O₅)	0–10	0.03
dextrose anhydr. (C₆H₁₂O₆)	0–60	0.02
dextrose hydr. (C₆H₁₂O₆·H₂O)	0–66	0.02
d-fructose (C₆H₁₂O₆)	0–70	0.02
inulin ((C₆H₁₀O₅)_x)	0–10	0.03
lactose anhydr. (C₁₂H₂₂O₁₁)	0–18	0.02
lactose hydr. (C₁₂H₂₂O₁₁·H₂O)	0–18.95	0.02
maltose anhydr. (C₁₂H₂₂O₁₁)	0–60	0.02
maltose hydr. (C₁₂H₂₂O₁₁·H₂O)	0–63.16	0.02
d-mannitol (C₆H₁₄O₆)	0–15	0.03
sucrose (C₁₂H₂₂O₁₁)	0–100	0.02

Δ The specified accuracy is based on the underlying literature tables

Material characterization

In industries like the petrochemical industry the density of a product is a very important characterization number or quality parameter. Standards such as those defined by ASTM define a certain density for every product (e.g. fuels, lubricating oils, or crude oils). Density measurement ensures these materials can be characterized and the quality of each product defined.

Academic research

Density is also commonly used as a standard parameter in academic research to investigate the special physical behavior of a product. In petrochemistry, for example, scientists measure the density of gasoline at different pressures and temperatures in the laboratory to find out how it will react once injected into an engine.

Quality control based on density

Another important application of density measurement is quality control – not only in the soft drink or petrochemical industry but also in the production of alcoholic beverages (beer, spirits, wine), fuels (including biodiesel and bioethanol), cosmetics, personal care products, pharmaceuticals, and many more.

Filling volume control

Whereas some products are quantified by weight, others are filled, paid, or taxed based on their volume. A well-proven procedure is to measure the weight of a fluid product with a balance, and then calculate its filling volume using the sample’s density. This procedure is usually applied where direct volume measurement is not possible (e.g., in the beverage, petroleum, or chemical industries).

The filling volume of a certain sample weight can be calculated based on the sample’s apparent density:

$$ V = { W \over \rho _{app}}$$

Equation 1: The filling volume V is defined as weight in air W divided by apparent density ρₐₚₚ of the sample

Conclusion

Countless analytical methods are used in today’s laboratories, whether in research facilities or industrial plants. Density measurement is employed not only to specify and describe pure substances, but also to determine concentrations of binary mixtures. It provides important information about the composition of mixtures, which is useful during quality control or when determining filling volume during the bottling of a product.

References

Fehlauer, H., and H. Wolf. 2006. "Density Reference Liquids Certified by the Physikalisch-Technische Bundesanstalt." Measurement Science and Technology 17: 2588–2592.

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Frequently Viewed

Density Measurement Applications

Density-based concentration determination

Acids

Bases

Alcohols

Ethanol

Inorganic salts

Others

Extract / sugars

Material characterization

Academic research

Quality control based on density

Filling volume control

Conclusion

References

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