Skip to main content

Mole

 A mole is defined as the amount(mass) of a substance that contains 6.022 × 10²³number of particles (atoms, molecules or formula units). It establishes a link between mass of a substance and number of particles as shown in summary of molar calculations.

•It is abbreviated as 'mol'.

Mass of a substance is either one of the following: atomic mass, molecular mass or formula mass. These masses are expressed in atomic mass units (amu). But when these masses are expressed in grams, they are called as molar masses.

 •Scientists have agreed that Avogadro's number of particles are present in one molar mass of a substance. Thus, quantitative definition of mole is the atomic mass, molecular mass or formula mass of a substance expressed in grams is called mole.

For example:

Atomic mass of carbon expressed as 12 g = 1 mol of carbon

Molecular mass of H2O expressed as 18 g = 1 mol of water

Molecular mass of H2SO4 expressed as 98 g = 1 mol of H2SO4

Formula mass of NaCl expressed as 58.5 g = 1 mol of NaCl

 •The relationship between mole and mass can be expressed as:


Or,

 Mass of substance (g) = number of moles x molar mass

Summary showing a relationship between a substance and a mole.



Comments

Post a Comment

Popular posts from this blog

Oxygen Cycle

It involves the inter- change of oxygen between the elemental form of gaseous O2, contained in a huge reservoir in the atmosphere, and chemically bound O in CO2, H2O, minerals, and organic matter. It is strongly tied with other elemental cycles, particularly the carbon cycle. Elemental oxygen becomes chemically bound by various energy-yielding processes, particularly combustion and metabolic processes in organisms. It is released in photosynthesis. This element readily combines with and oxidizes other species such as carbon in the process of aerobic respiration, or carbon and hydrogen in the combustion of fossil fuels such as methane: CH4 +  2O2    →   CO2    +  2H2O Elemental oxygen also oxidizes inorganic substances such as iron(II) in minerals: 4FeO4   +   O2   →    2Fe3O3 A particularly important aspect of the oxygen cycle is stratospheric ozone O3. A relatively small concentration of ozone in the strato...
Post a Comment
Read more

Structure of Atom (Part 6)

Bohr's Atomic Theory: Keeping in view the defects in Rutherford's Atomic Model, Neil Bohr presented another model of atom in 1913.The Quantum Theory of Max Planck was used as foundation for this model. According to Bohr's model, revolving electron in an atom does not absorb or emit energy continuously. The energy of a revolving electron is 'quantized' as it revolves only in orbits of fixed energy, called 'energy levels' by him.  The Bohr's atomic model was based upon the following postulates: i. The hydrogen atom consists of a tiny nucleus and electrons are revolving in one of circular orbits of radius ‘r’ around the nucleus. ii. Each orbit has a fixed energy that is quantized.  iii. As long as electron remains in a particular orbit, it does not radiate or absorb energy. The energy is emitted or absorbed only when an electron jumps from one orbit to another. iv. When an electron jumps from lower orbit to higher orbit, it absorbs energy and when it jumps ...
Post a Comment
Read more

Nitrogen Cycle

 Nitrogen occurs prominently in all the spheres of the environment. The atmosphere is 78% elemental nitrogen, N2, by volume and comprises an inexhaustible reservoir of this essential element. Nitrogen, although constituting much less of biomass than carbon or oxygenoxygen, is an essential constituent of proteins. The N2 molecule is very stable so that breaking it down into atoms that can be incorporated with inorganic and organic chemical forms of nitrogen is the limit- ing step in the nitrogen cycle. This does occur by highly energetic processes in lightning discharges that produce nitrogen oxides. Elemental nitrogen is also incorporated into chemically bound forms. or fixed by biochemical processes mediated by microorganisms. The biological nitrogen is mineral- ized to the inorganic form during the decay of biomass. Large quantities of nitrogen are fixed synthetically under high-temperature and high-pressure conditions according to the following over- all reaction:     ...
Post a Comment
Read more