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Mole Concept

Last Updated on By Mrs Shilpi Nagpal

Question 1 Define a mole?
 
Question 2 What is the value of Avogadro’s constant?
 
Question 3 Define mole of an atom?
 
Question 4 Define mole of a molecule?
 
Question 5 Write the formula to calculate the number of moles?
 
Mole Concept
 
In a chemical reaction equation,it is more convenient to use quantity of substance in number of its molecules or atoms rather than their masses,so we use a new unit called MOLE.

If we weigh an element equal to its atomic mass in grams,then it contains 6.022×1023 atoms of the element.The gram atomic mass of the element as well as 6.022×1023 atoms of the element, both represent 1 mole of element.1 mole of any species (atoms,molecules,ions) is equal to its atomic mass or molecular mass in grams.

No. of particles(atoms, molecules, ions) in 1 mole=6.022×1023

This number is called as AVOGADRO’S CONSTANT

1 mole of atom=6.022×1023atoms

1 mole of molecules=6.022×1023molecules

Mole of atoms

1 mole of atoms of an element has a mass equal to the gram atomic mass of the element.

For Ex: 1 mole of oxygen atoms=16 grams

The symbol of an element represents 1 mole of atoms of that element.

o represents 1 mole of oxygen atoms.

2 o represents 2 moles of oxygen atoms.

Mole of Molecule

1 mole of molecules of a substance has a mass equal to the gram molecular mass of the substance.

For Ex:The gram molecular mass of oxygen is 32 grams.‎O2  represents 1 mole of oxygen molecule

2 ‎‎O2  represents 2 mole of oxygen molecule

1 mole of sulphuric acid,, H2SO4 contains 2 moles of hydrogen atom,1 mole of sulphur atom,4 moles of oxygen atoms.
 
1 mole of H atom=1u=1g=6.022×1023 H atoms
1 mole of molecule=2u=2g=6.022×1023 molecule
1 mole of water molecule=18u=18g=6.022×1023 water molecule
1 mole of sodium atom=23u=23g=6.022×1023 sodium atom
 
 
Mole represents:
1) 6.022×1023 atoms,molecules or ions of a substance.
2)The amount of a substance equal to its gram atomic mass or molecular mass.
3)A definite number of atoms,molecules or ions of a substance.

number of moles

mole of substance
 

About Mrs Shilpi Nagpal

Author of this website, Mrs. Shilpi Nagpal is MSc (Hons, Chemistry) and BSc (Hons, Chemistry) from Delhi University, B.Ed. (I. P. University) and has many years of experience in teaching. She has started this educational website with the mindset of spreading free education to everyone.

Reader Interactions

Comments

  5. samhitha says

    It’s not 6.022 x 1023 , it is 6.022 x 10 to the power 23 ..pls its my request to not publish wrong information …plss .

  6. Mrs Shilpi Nagpal says

    Thank u so much for pointing out the error.It was formatting error in word press.I have published the correct information only.

  7. Arpan Dutta says

    I can’t understand the mole concept but by reading this I got the idea about the molar concept. Thank u.

  18. Shilpa says

    it was really helpful for me to study during exam.
    i was actually struggling to learn and by heart this mole concept.
    but after referring to your notes i understood this concept crystal clear.
    i helped my friends by sharing this website link too.
    and we are thankful to you madam.
    thank you ma’am .

  24. parth says

    i understood mole concept very nicely by reading this……
    thanks a lot shilpa mam………..

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