Mole (unit)

The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6.022 140 76 × 1023 elementary entities. This number is the fixed numerical value of the Avogadro constant, NA, when expressed in mol−1, and is called the Avogadro number. The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, or any other particle or specified group of particles.[1]

The term gram-molecule was formerly used for essentially the same concept.[2] The term gram-atom has been used for a related but distinct concept, namely a quantity of a substance that contains Avogadro's number of atoms, whether isolated or combined in molecules. Thus, for example, 1 mole of MgBr2 is 1 gram-molecule of MgBr2 but 3 gram-atoms of MgBr2.[3][4]

Definition and related concepts

As of 2017 as defined by IUPAC, the mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6.022 140 76 × 1023 elementary entities. This number is the fixed numerical value of the Avogadro constant, NA, when expressed in mol−1, and is called the Avogadro number. The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, or any other particle or specified group of particles.[1]

The molar mass of a substance is its mass divided by its amount of substance, which is a constant for any given substance. Since the unified atomic mass unit (symbol: u, or Da) is defined as 1/12 of the mass of the 12C atom, it follows that the molar mass of a substance, measured in grams per mole, is numerically equal to its mean atomic or molecular mass measured in Da.

The number of constitutive entities in a sample of a substance is technically called its (chemical) amount. Therefore, the mole is a unit for that physical quantity. One can determine the chemical amount of a known substance, in moles, by dividing the sample's mass by the substance's molar mass.[5] Other methods include the use of the molar volume or the measurement of electric charge.[5]

The mass of one mole of a substance depends not only on its molecular formula, but also on the proportion of the isotopes of each element present in it. For example, one mole of calcium-40 is 39.96259098±0.00000022 grams, whereas one mole of calcium-42 is 41.95861801±0.00000027 grams, and one mole of calcium with the normal isotopic mix is 40.078±0.004 grams.

Since the definition of the gram is not (as of 2011) mathematically tied to that of the atomic mass unit, the number of molecules per mole NA (the Avogadro constant) must be determined experimentally. The value adopted by CODATA in 2010 is NA = (6.02214129±0.00000027)×1023 mol−1.[6] In 2011 the measurement was refined to (6.02214078±0.00000018)×1023 mol−1.[7]

The number of moles of a sample is the sample mass divided by the molar mass of the material.

Other Languages
العربية: مول
অসমীয়া: ম'ল
asturianu: Mol
azərbaycanca: Mol
Bân-lâm-gú: Mol
беларуская: Моль
беларуская (тарашкевіца)‎: Моль
български: Мол
བོད་ཡིག: མོལ།
bosanski: Mol (jedinica)
brezhoneg: Mol
català: Mol
Чӑвашла: Моль
čeština: Mol
Cymraeg: Môl (uned)
Deutsch: Mol
eesti: Mool
Ελληνικά: Γραμμομόριο
español: Mol
Esperanto: Molaro (kemio)
euskara: Mol
فارسی: مول
français: Mole (unité)
Gaeilge: Mól
galego: Mol
한국어: 몰 (단위)
Հայերեն: Մոլ
हिन्दी: मोल (इकाई)
Bahasa Indonesia: Mol
íslenska: Mól
italiano: Mole
עברית: מול
ಕನ್ನಡ: ಮೋಲ್
ქართული: მოლი
қазақша: Моль
Kreyòl ayisyen: Mòl
kurdî: Mol
Кыргызча: Моль
latviešu: Mols
Lëtzebuergesch: Mol
lietuvių: Molis (vienetas)
Ligure: Mole
magyar: Mól
македонски: Мол
मराठी: मोल (एकक)
Bahasa Melayu: Mol
монгол: Моль
Nederlands: Mol (eenheid)
日本語: モル
Nordfriisk: Mol
norsk nynorsk: Mol
occitan: Mòl (unitat)
ਪੰਜਾਬੀ: ਮੋਲ (ਇਕਾਈ)
پنجابی: مول
Piemontèis: Mòle
Plattdüütsch: Mol (Eenheit)
polski: Mol
português: Mol
română: Mol
русиньскый: Мол
русский: Моль
සිංහල: මවුලය
Simple English: Mole (unit)
slovenčina: Mol (jednotka SI)
slovenščina: Mol (enota)
Soomaaliga: Mole
српски / srpski: Мол (јединица)
srpskohrvatski / српскохрватски: Mol (jedinica)
suomi: Mooli
svenska: Mol
Tagalog: Mole (yunit)
தமிழ்: மோல்
татарча/tatarça: Моль
ไทย: โมล
Türkçe: Mol (birim)
українська: Моль (одиниця)
Tiếng Việt: Mol
文言: 摩爾
Winaray: Mol
粵語: 摩爾