Mole Concept

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Introduction:-

Mole is a unit which represents 6.022  x  1023  particles  ( atoms, molecules or ions etc) irrespective of their nature. The number 6.022  x  1023  is called Avgadro’s number and is represented by NA .  The calculation of this number is based on the Faraday’s laws of electrolysis.
A mole also represents gram molecular mass (GMM) of the substance. For gases, a mole also stands for gram molecular volume (GMV). i.e 22.4 L at Standard Temperature and Pressure (STP)

Mathematical calculation:-

1 Mole of atoms = 6.022  x 1023  atoms
1 Mole of molecules = 6.022 x 1023 molecules = GMM of substance
  • Gram atom is defined as atomic weight expressed in gram. It contains 6.022 x 1023
                                             Gram atomic mass
  • Mass of 1 atom = ——————————-                                                                                6.022 x 1023
  • 1 amu = 66 x 1024 g  because, 6.022 x 1023 amu = 1 g
  • Atomicity is number of atoms present in a molecule.
 
Example :- Calculate mass of one atom of nitrogen in gram.    
Solution:-  Mass of 6.022 x 1023  atoms of nitrogen = gram atomic  mass of                       nitrogen = 14 .
                   Mass of 1 atom = GAM/ NA                                                          
                                                             14
Mass of 1 atom of nitrogen = —————————
                                                      6.022 x 1023  
    = 2.32 x 10-23 g

Why Do We Use Moles?

It is a practical approach to express amounts of a chemical material, the mole idea is used. Because atoms and molecules are so tiny, it would be strange to employ a unit of measurement like grams, which is frequently used in everyday life, without a conversion factor.
Moles facilitate chemistry computations. Atomic and molecular processes give rise to chemical reactions, and chemists can weigh and quantify particles by utilising moles. This is necessary to ensure that the right amounts of reactants are utilised in chemical reactions and to precisely forecast their results.
Mole concept-Molecules
Molecules

How Do We Measure Moles?

We use a substance’s molar mass to calculate how many moles it contains. Mass of one mole of a certain substance is known as the molar mass, and it is commonly stated in grams per mole (g/mol). For example, one mole of carbon atoms weighs 12 grams because the molar mass of carbon is 12 g/mol.
The following formula can be used to determine the number of moles (n) in a given mass (m) of a substance:
                                 n = m / M
where:
  • n = number of moles,
  • m = mass of the substance in grams,
  • M = molar mass of the substance in grams per mole.
For example, if you have 24 grams of carbon, the number of moles of carbon would be:        
               24 g
N = ————– = 2 moles
        12 g / mol

Moles in Chemical Reactions:-

Chemical reactions are subject to the law of conservation of mass, it is essential to understand the idea of a mole. According to this law, a chemical reaction cannot produce or destroy matter.
As a result, before and after the reaction, the number of atoms in each element must be constant. Conservation of mass is represented by chemists using balanced chemical equations, in which the coefficients of each material show how many moles are needed or produced.
For example, consider the reaction between hydrogen and oxygen to form water:
                                2H2​+O2​→2H2​O
According to this equation, two moles of hydrogen gas and one mole of oxygen gas combine to form two moles of water.

Applications of the Mole Concept:-

Real-world uses for the mole concept in everyday life in addition to theoretical chemistry. For example, the mole idea is applied in medicine to determine the appropriate dosage of medications based on molecular weight.
It is used in environmental research to figure out how much pollution is in the air or water. Idea of a mole can be useful in cooking as well as for converting between the mass and number of molecules, particularly in molecular gastronomy.

Conclusion:-

Idea of a mole is a useful tool in chemistry that makes counting and measuring atoms and molecules easier. It makes it simpler to understand and forecast the results of chemical interactions by allowing us to connect macroscopic quantities, such as grams and liters, to the microscopic world of atoms and molecules.
Mole Concept-Microscope
microscope
Mole concept is a fundamental principle in chemistry that provides a way to count and measure substances at the atomic and molecular levels. One mole represents 6.022×1023  (atoms, molecules, ions, etc.) of a substance, which is known as Avogadro’s number. This concept is crucial because it allows chemists to relate macroscopic quantities of materials (grams) to the number of particles, facilitating calculations in chemical reactions and quantitative analysis.
Molar mass of a substance is calculated by summing the atomic masses of all the elements in its chemical formula, expressed in grams per mole (g/mol). For example, the molar mass of water (H₂O) is calculated as (2×1.01)+16.00=18.02 g/mol. Molar mass is useful because it connects the mass of a substance to the number of moles, allowing for conversions between mass, number of moles, and number of particles.
Empirical formula of a compound represents the simplest whole-number ratio of elements in that compound, The molecular formula shows the actual number of each type of atom in a molecule. The mole concept helps in determining both by analysing the moles of each element present in a sample and then deriving the ratios. For instance, the empirical formula of hydrogen peroxide is HO, while it is molecular formula is H₂O₂.
Mole concept is integral to gas laws, especially Avogadro’s law, which states that equal volumes of gases, at the same temperature and pressure, contain an equal number of moles.  This principle implies that the volume of a gas is directly proportional to the number of moles, provided temperature and pressure are constant. For example, at standard temperature and pressure (STP), one mole of any gas occupies 22.4 liters.
Mole concept in a chemical reaction, consider the combustion of methane: CH4+2O2​→CO2​+2H2​O  Here, one mole of methane reacts with two moles of oxygen to produce one mole of carbon dioxide and two moles of water. Moles of reactants, we can calculate the moles (and thus the mass) of the products formed. If 16 grams (1 mole) of methane is burned, it will require 64 grams (2 moles) of oxygen and produce 44 grams (1 mole) of CO₂ and 36 grams (2 moles) of H₂O.

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