مول
یک مول (Mole) مقدار ماده خالصی است که شامل عدد آووگادرو واحد اصلی باشد. این واحد، یکی از آحاد SI است. تعریف مول مقدار ماده خالصی است که تعداد واحدهای مستقل اصلی آن دقیقا برابر با تعداد اتم های 12 گرم کربن 126C باشد.
پس، نمونه ای از یک عنصر که جرم آن بر حسب گرم از لحاظ عددی برابر با وزن اتمی آن عنصر باشد، شامل یک مول از اتم های عنصر، یعنی شامل عدد آووگادرو اتم است. مثلا وزن اتمی بریلیم 9.01218 است. بنابراین:
9.01218g Be=1 mole Be=6.02205×1023 اتم برلیم
یک مول ماده مولکولی مرکب از عدد آووگادرو مولکول و جرمی بر حسب گرم دارد که از لحاظ عددی برابر با وزن مولکولی آن ماده است. مثلا وزن مولکولی H2O، برابر با 18.02 است. پس:
18.02 g H2O=1 mol H2O=6.022×1023 H2O مولکول
در مورد جامدات یونی نیز به همین شکل عمل می شود. به عنوان مثال در مورد BaCl2 یک مول برابر با 208.3 گرم است ه همان وزن فرمولی BaCl2 است. در واقع یک مول BaCl2 شامل:
1 mol Ba2+=6.02×1023 Ba2+=137.3 g باریم
2 mol Cl-=2(6.02×1023)Cl-=2(35.5)g Cl-=71.0 g کلر
که در مجموع عبارتست از:
1 mol BaCl2=6.02×1023 BaCl2=208.3 g BaCl2
منابع و پیوندها
گردآوری شده توسط دپارتمان پژوهشی شرکت پاکمن
چارلز مورتیمر ، شیمی عمومی ، جلد اول ، مرکز نشر دانشگاهی ، 1381.
برداشت از مطالب سایت با ذکر منبع بلامانع است
مول از دید wikipedia.org
The mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as an amount of a substance that contains as many elementary entities (e.g., atoms, molecules, ions, electrons) as there are atoms in 12 grams of pure carbon-12 (12C), the isotope of carbon with atomic weight 12. This corresponds to a value of 6.02214179(30)×1023 elementary entities of the substance. It is one of the base units in the International System of Units, and has the unit symbol mol. The mole is widely used in chemistry, instead of units of mass or volume, as a convenient way to express the amounts of reactants and products of chemical reactions. For example, the chemical equation 2 H2 + O2 → 2 H2O implies that 2 mol of dihydrogen and 1 mol of dioxygen react to form 2 mol of water. The mole may also be used to express the number of atoms, ions, or other elementary entities in some sample. The concentration of a solution is commonly expressed by its molarity, the number of moles of the dissolved substance per litre of solution. The number of molecules in a mole (known as Avogadro's number) is defined so that the mass of one mole of a substance, expressed in grams, is exactly equal to the substance's mean molecular weight. For example, the mean molecular weight of natural water is about 18.015, so one mole of water is about 18.015 grams. This property considerably simplifies many chemical and physical computations. The name gram-molecule was formerly used for essentially the same concept. The name gram-atom (abbreviated gat.) 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 MgB2 is 1 gram-molecule of MgB2 but 3 gram-atoms of MgB2...more
مول از دید cliffsnotes.com
The mole is the most common unit used to express the quantity of a chemical substance. For all solids, liquids, and gases, you can convert mass to moles (or moles to mass). For gases, you should memorize the following conversion of volume to moles (or moles to volume): at 0°C and 1 atmosphere pressure (known as standard temperature and pressure or STP), one mole of any gas occupies approximately 22.4 liters. Therefore, the preceding reaction describing the oxidation of carbon means that 12 grams of carbon burned at STP in 22.4 liters of O2 yields 22.4 liters of carbon dioxide. Many substances do not exist as molecules. For example, the atoms in most inorganic solids are in a three-dimensional structure in which each atom is surrounded by a number of other atoms. In crystals of sodium chloride, no distinct Na and Cl pair can be called a molecule, because each sodium is surrounded by 6 chlorine and each chlorine is surrounded by 6 sodium...more
مول از دید physics.nist.gov
Following the discovery of the fundamental laws of chemistry, units called, for example, gram-atom and gram-molecule, were used to specify amounts of chemical elements or compounds. These units had a direct connection with atomic weights and molecular weights, which were in fact relative masses. Atomic weights were originally referred to the atomic weight of oxygen, by general agreement taken as 16. But whereas physicists separated isotopes in the mass spectrograph and attributed the value 16 to one of the isotopes of oxygen, chemists attributed that same value to the (slightly variable) mixture of isotopes 16, 17, and 18, which was for them the naturally occurring element oxygen. Finally, an agreement between the International Union of Pure and Applied Physics (IUPAP) and the International Union of Pure and Applied Chemistry (IUPAC) brought this duality to an end in 1959/60. Physicists and chemists have ever since agreed to assign the value 12, exactly, to the atomic weight, correctly the relative atomic mass, of the isotope of carbon with mass number 12 (carbon 12, 12C). The unified scale thus obtained gives values of relative atomic mass...more
