Mole is a unit of measurement used in chemistry to express amounts of a chemical substance, defined as the amount of any 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 relative atomic mass 12. This corresponds to the Avogadro constant, which has a value of 6.02214129(27)×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 and corresponds with the dimension symbol N. Mole is one of basic concepts to learn chemistry.
The mole is widely used in chemistry instead of units of mass or volume as a convenient way to express amounts of reactants or of products of chemical reactions. For example, the chemical equation 2 H2 + O2 → 2 H2O implies that 2 mol of dihydrogen (H2) and 1 mol of dioxygen (O2) react to form 2 mol of water (H2O). The mole may also be used to express the number of atoms, ions, or other elementary entities in a given sample of any substance. The concentration of a solution is commonly expressed by its molarity, defined as the number of moles of the dissolved substance per liter of solution.
From Wikipedia.
Moles give us a consistent method to convert between atoms/molecules and grams. It's simply a convenient unit to use when performing calculations. Okay... you may not find it too convenient when you are first learning how to use it, but once you become familiar with it, a mole will be as normal a unit as, say, a dozen or a byte.
Examples on how to calculate the moles of a substance?
Suppose you have a sample of weight 'w' in gms which is chemically homogeneous
1. No of moles of atoms = w/ atomic weight
(If your sample is single element like 02 ,N2 then u can use this formula
Ex- suppose a sample of oxygen have 32 gms
Then no of moles of atoms of Oxy. = 32/16 = 2 moles
In other words this tells you that ur sample contains 2 moles of Oxy. atoms or 2 x 6.023 x 10 ^23 no. of Oxy. atoms
2. No. of moles of molecules= w / molecular weight
If your sample is single element or compound like NaCl, AgNO3 etc then u can use this formula
For the above example
Then no of moles of molecules of Oxy. = 32/32 =1 mole
In other words this tells you that ur sample contains 1 mole of Oxy. molecules or 6.023 x 10 ^23 no. of Oxy. molecules
Ex-2 117 gms of common salt (NaCl or Sodium Chloride)
No. of moles of molecules = 117 / (23 + 35.5) = 2 moles
Where chemical change in the reactions lead to new entities.
Now lets see some example problems about mole calculation and the typical solution for them
Problem 1:
determine the number of moles from 25g of NaCl?
Answer:
use the formula: number of moles = mass / molar mass
mass is 25g, molar mass is 58.44g/mol
Problem 2:
from 2Al + 3Cl2 --> 2AlCl3
a) how many moles of AlCl3 are produced from 6 moles of Cl2?
b) Calculate the mass of AlCl3 produced from 10g of Al
Answer is:
The equation tells you that 3 moles of Cl2 can produce 2 moles of AlCl3, so if you have twice as much Cl2 (6 moles), how much AlCl3?
AlCl3 = 4mol
Many explanation of measurment units in chemistry will be added.
Follow. like, share... spread the acknowledgement.
The mole is widely used in chemistry instead of units of mass or volume as a convenient way to express amounts of reactants or of products of chemical reactions. For example, the chemical equation 2 H2 + O2 → 2 H2O implies that 2 mol of dihydrogen (H2) and 1 mol of dioxygen (O2) react to form 2 mol of water (H2O). The mole may also be used to express the number of atoms, ions, or other elementary entities in a given sample of any substance. The concentration of a solution is commonly expressed by its molarity, defined as the number of moles of the dissolved substance per liter of solution.
From Wikipedia.
Moles give us a consistent method to convert between atoms/molecules and grams. It's simply a convenient unit to use when performing calculations. Okay... you may not find it too convenient when you are first learning how to use it, but once you become familiar with it, a mole will be as normal a unit as, say, a dozen or a byte.
Examples on how to calculate the moles of a substance?
Suppose you have a sample of weight 'w' in gms which is chemically homogeneous
1. No of moles of atoms = w/ atomic weight
(If your sample is single element like 02 ,N2 then u can use this formula
Ex- suppose a sample of oxygen have 32 gms
Then no of moles of atoms of Oxy. = 32/16 = 2 moles
In other words this tells you that ur sample contains 2 moles of Oxy. atoms or 2 x 6.023 x 10 ^23 no. of Oxy. atoms
2. No. of moles of molecules= w / molecular weight
If your sample is single element or compound like NaCl, AgNO3 etc then u can use this formula
For the above example
Then no of moles of molecules of Oxy. = 32/32 =1 mole
In other words this tells you that ur sample contains 1 mole of Oxy. molecules or 6.023 x 10 ^23 no. of Oxy. molecules
Ex-2 117 gms of common salt (NaCl or Sodium Chloride)
No. of moles of molecules = 117 / (23 + 35.5) = 2 moles
Where chemical change in the reactions lead to new entities.
Now lets see some example problems about mole calculation and the typical solution for them
Problem 1:
determine the number of moles from 25g of NaCl?
Answer:
use the formula: number of moles = mass / molar mass
mass is 25g, molar mass is 58.44g/mol
Problem 2:
from 2Al + 3Cl2 --> 2AlCl3
a) how many moles of AlCl3 are produced from 6 moles of Cl2?
b) Calculate the mass of AlCl3 produced from 10g of Al
Answer is:
The equation tells you that 3 moles of Cl2 can produce 2 moles of AlCl3, so if you have twice as much Cl2 (6 moles), how much AlCl3?
AlCl3 = 4mol
Many explanation of measurment units in chemistry will be added.
Follow. like, share... spread the acknowledgement.
