![Absinthe ABV](https://upload.wikimedia.org/wikipedia/commons/7/74/Absinthe_ABV.jpg)
Alcohol by volume (abbreviated as ABV, abv, or alc/vol) is a standard measure of how much alcohol (
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
) is contained in a given volume of an
alcoholic beverage
An alcoholic beverage (also called an alcoholic drink, adult beverage, or a drink) is a drink that contains ethanol, a type of alcohol that acts as a drug and is produced by fermentation of grains, fruits, or other sources of sugar. The c ...
(expressed as a
volume percent
In chemistry and fluid mechanics, the volume fraction φ''i'' is defined as the volume of a constituent ''V'i'' divided by the volume of all constituents of the mixture ''V'' prior to mixing:
:\phi_i = \frac
Being dimensionless quantity, dim ...
). It is defined as the number of millilitres (mL) of pure
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
present in of solution at . The number of millilitres of pure ethanol is the mass of the ethanol divided by its
density
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...
at , which is . The ABV standard is used worldwide. The
International Organization of Legal Metrology
The International Organization of Legal Metrology (french: Organisation Internationale de Métrologie Légale - OIML), is an intergovernmental organisation that was created in 1955 to promote the global harmonisation of the legal metrology procedu ...
has
tables of density of water–ethanol mixtures at different concentrations and temperatures.
In some countries, e.g.
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, alcohol by volume is often referred to as degrees Gay-Lussac (after the French chemist
Joseph Louis Gay-Lussac
Joseph Louis Gay-Lussac (, , ; 6 December 1778 – 9 May 1850) was a French chemist and physicist. He is known mostly for his discovery that water is made of two parts hydrogen and one part oxygen (with Alexander von Humboldt), for two laws ...
), although there is a slight difference since the Gay-Lussac convention uses the
International Standard Atmosphere
The International Standard Atmosphere (ISA) is a static atmospheric model of how the pressure, temperature, density, and viscosity of the Earth's atmosphere change over a wide range of altitudes or elevations. It has been established to provide a ...
value for temperature, .
Volume change
![Excess Volume Mixture of Ethanol and Water](https://upload.wikimedia.org/wikipedia/commons/4/45/Excess_Volume_Mixture_of_Ethanol_and_Water.png)
Mixing two solutions of alcohol of different strengths usually causes a change in volume. Mixing pure water with a solution less than 24% by mass causes a slight increase in total volume, whereas the mixing of two solutions above 24% causes a decrease in volume. The phenomenon of volume changes due to mixing dissimilar solutions is called "
partial molar volume
In thermodynamics, a partial molar property is a quantity which describes the variation of an extensive property of a solution or mixture with changes in the molar composition of the mixture at constant temperature and pressure. It is the parti ...
". Water and ethanol are both
polar
Polar may refer to:
Geography
Polar may refer to:
* Geographical pole, either of two fixed points on the surface of a rotating body or planet, at 90 degrees from the equator, based on the axis around which a body rotates
* Polar climate, the c ...
solvents. When water is added to ethanol, the smaller water molecules are attracted to the ethanol's hydroxyl group, and each molecule alters the polarity field of the other. The attraction allows closer spacing between molecules than is usually found in non-polar mixtures.
Thus, ABV is not the same as
volume fraction
In chemistry and fluid mechanics, the volume fraction φ''i'' is defined as the volume of a constituent ''V'i'' divided by the volume of all constituents of the mixture ''V'' prior to mixing:
:\phi_i = \frac
Being dimensionless, its unit is ...
expressed as a percentage. Volume fraction, which is widely used in chemistry (commonly denoted as v/v), is defined as the volume of a particular component divided by the sum of all components in the mixture when they are measured separately. For example, to make 100 ml of 50% ABV ethanol solution, water would be added to 50 ml of ethanol to make up exactly 100 ml. Whereas to make a 50% v/v ethanol solution 50 ml of ethanol and 50 ml of water could be mixed but the resulting volume of solution will measure less than 100 ml due to the change of volume on mixing, and will contain a higher concentration of ethanol. The difference is not large, with the maximum difference being less than 2.5%, and less than 0.5% difference for concentrations under 20%.
Threshold levels
Legal thresholds
Some drinks have requirements of alcoholic content in order to be certified as a certain alcohol brand or label. Some alcoholic drinks may be considered legally as non-alcoholic in spite of having relatively high alcohol levels such as in Finland where products under 3 degrees can be sold legally as alcohol-free.
Low-alcohol beers (0.5<) are considered in some countries such as Iran as permitted (or "halal" under Muslim vocabulary) despite alcohol being banned. However, the level of alcohol-free beers is typically the lowest commercially sold 0.05.
Biological thresholds
It is near impossible for a healthy person to become intoxicated drinking low-alcohol drinks. The low concentration severely limits the rate of intake, which is easily dispatched by human metabolism. Quickly drinking 1.5 L of 0.4% ABV beer in an hour resulted in a maximum of 0.0056%
BAC
BAC or Bac may refer to:
Places
* Bac, Rožaje, Bac, a village in Montenegro
* Baile Átha Cliath, Irish language name for Dublin city.
* Bîc River, aka ''Bâc River'', a Moldovan river
* Baç Bridge, bridge in Turkey
* Barnes County Municipal A ...
in a study of German volunteers. Healthy human kidneys can only excrete 0.8–1.0 L of water per hour, making
water intoxication
Water intoxication, also known as water poisoning, hyperhydration, overhydration, or water toxemia, is a potentially fatal disturbance in brain functions that results when the normal balance of electrolytes in the body is pushed outside safe lim ...
likely to set in before any alcoholic intoxication.
The process of
ethanol fermentation
Ethanol fermentation, also called alcoholic fermentation, is a biological process which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products. Because yeasts perform this ...
will slow down and eventually come to a halt as the alcohol produced becomes too concentrated for the yeast to tolerated, defining an upper limit of ABV for non-distilled alcoholic drinks. The typical tolerance for beer yeasts is at 8–12%, while wine yeasts typically range from 14–18%, with speciality ones reaching 20% ABV. Any higher would require distillation, producing
liquor
Liquor (or a spirit) is an alcoholic drink produced by distillation of grains, fruits, vegetables, or sugar, that have already gone through alcoholic fermentation. Other terms for liquor include: spirit drink, distilled beverage or hard ...
.
Typical levels
Details about typical amounts of alcohol contained in various beverages can be found in the articles about them.
Practical estimation of alcohol content
During the production of wine and beer,
yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...
is added to a sugary solution. During fermentation, the yeasts consume the sugars and produce alcohol. The density of sugar in water is greater than the density of alcohol in water. A
hydrometer
A hydrometer or lactometer is an instrument used for measuring density or relative density of liquids based on the concept of buoyancy. They are typically calibrated and graduated with one or more scales such as specific gravity.
A hydrometer ...
is used to measure the change in
specific gravity
Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...
(SG) of the solution before and after fermentation. The volume of alcohol in the solution can then be estimated. There are a number of empirical formulae which brewers and winemakers use to estimate the alcohol content of the liquor made.
Specific gravity is the density of a liquid relative to that of water, i.e., if the density of the liquid is 1.05 times that of water, it has a specific gravity of 1.05. In UK brewing usage, it is customary to regard the reference value for water to be 1000, so the specific gravity of the same example beer would be quoted as 1050. The formulas here assume that the former definition is used for specific gravity.
Wine
The simplest method for wine has been described by English author
C.J.J. Berry:
Beer
One calculation for beer is:
For higher ABV above 6% many brewers use this formula:
Other methods of specifying alcohol content
Alcohol proof
Another way of specifying the amount of alcohol content is alcohol ''proof'', which in the United States is twice the alcohol-by-volume (ABV) number. This may lead to confusion over similar products bought in varying regions that have different names on country-specific labels. For example,
Stroh
Stroh Austria GmbH is an Austrian manufacturer of rum, especially spiced rums and high-proof rums used in warm drinks and cooking. The Stroh Rum brand is one of the best-known spirits from Austria. The name is widely used as a generic synonym f ...
rum that is 80% ABV is advertised and labeled as ''Stroh 80'' when sold in Europe, but is named ''Stroh 160'' when sold in the United States.
In the United Kingdom proof is 1.75 times the number (expressed as a percentage). For example, 40% ABV is 80 proof in the US and 70 proof in the UK. However, since 1980, alcohol proof in the UK has been replaced by ABV as a measure of alcohol content, avoiding confusion between the UK and US proof standards.
Alcohol by weight
In the United States and India, a few states regulate and tax alcoholic beverages according to alcohol by weight (ABW), expressed as a
percentage of total mass. Some brewers print the ABW (rather than the ABV) on beer containers, particularly on
low-point versions of popular domestic beer brands. The ABV value of a beverage is always higher than the ABW.
Because ABW measures the proportion of the drink's mass which is alcohol, while ABV is the proportion of the drink's volume which is alcohol, the two values are in the same proportion as the drink's density is with the density of alcohol. Therefore, one can use the following equation to convert between ABV and ABW:
At relatively low ABV, the alcohol percentage by weight is about 4/5 of the ABV (e.g., 3.2% ABW is about 4% ABV).
[
] However, because of the
miscibility
Miscibility () is the property of two substances to mix in all proportions (that is, to fully dissolve in each other at any concentration), forming a homogeneous mixture (a solution). The term is most often applied to liquids but also appl ...
of alcohol and water, the conversion factor is not constant but rather depends upon the concentration of alcohol. At 0% and 100% ABV is equal to ABW, but at values in between ABV is always higher, up to ~13% higher around 60% ABV.
See also
*
Apparent molar property
In thermodynamics, an apparent molar property of a solution component in a mixture or solution is a quantity defined with the purpose of isolating the contribution of each component to the non-ideality of the mixture. It shows the change in the c ...
*
Excess molar quantity
In chemical thermodynamics, excess properties are properties of mixtures which quantify the non- ideal behavior of real mixtures. They are defined as the difference between the value of the property in a real mixture and the value that would exist ...
*
Standard drink
A standard drink is a measure of alcohol consumption representing a hypothetical beverage which contains a fixed amount of pure alcohol. A standard drink varies in volume depending on the alcohol concentration of the beverage (for example, a st ...
*
Unit of alcohol
Units of alcohol are used in the United Kingdom (UK) as a measure to quantify the actual alcoholic content within a given volume of an alcoholic beverage, in order to provide guidance on total alcohol consumption.
A number of other countries (in ...
*
Volume fraction
In chemistry and fluid mechanics, the volume fraction φ''i'' is defined as the volume of a constituent ''V'i'' divided by the volume of all constituents of the mixture ''V'' prior to mixing:
:\phi_i = \frac
Being dimensionless, its unit is ...
Notes
References
Bibliography
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External links
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{{DEFAULTSORT:Alcohol By Volume
Alcohol measurement