Mole Concept: Overview, Questions, Preparation

The mole concept is an easy term that allows the process of expressing the amount of a substance. Amedeo Avogadro, an Italian scientist, was the first scientist to acknowledge that elements could occur in molecules rather than as individual atoms. Every other measurement gets divided into two parts – numerical value and the units. In the subject Chemistry, the mole concept is described as the amount of a substance that contains exactly  6.022140761023 'essential entities' of that substance. This number (6.022140761023) is constant and popularly known as the Avogadro number or constant. It is often symbolised as a ‘NA’. 

The following formula can represent the number of moles of a substance in a given genuine sample,

n = N➗NA or n=N/NA

In the equation, n is the number of moles of a substance or elementary entity in an equation, and N is the total number of elementary entities in a sample, and NA is the constant of Avogadro.

( NA=6.022140761023)

The conveniently rounded version is 6.022 1023

Weightage of the chapters of Mole concept in Class 11 examination is of 7 marks and can expect a minimum of 2 questions from this chapter. 

1. How are you going to evaluate the number of water molecules in 90 grams of water?

Answer: The molar mass of water is roughly 18.  Therefore, 90 grams of water makes up a total of 5 moles. Each mole has 6.0221023 water molecules. The total number of water molecules or  H2O molecules in 90 grams of water is 30.1105115.

2. How do you evaluate the number of atoms of oxygen in 3 moles of O2?

Answer: As we know, one molecule of O2 = 2 oxygen atoms

hence, 1 mole of O2 = 6- mole oxygen atoms

= 6× 6.022 × 1023 = 36.132 ×1023 oxygen atom

3. How would you evaluate  the number of atoms of Cu in 0.635g of Cu?

Answer: No. of Moles of Cu

= Mass of Cu/Atomic mass

= 0.635/63.5

=0.01 mole

Now the equation will be as under, 

No. of Cu atoms

= No. of moles × Avogadro constant

= 0.01 × 6.022 × 1023

= 6.022 × 1023 Cu atoms.

Q: What is Mole concept in chemistry?

Q: Who came up with the mole concept?

Q: What is the concept of mole and molar mass?

Q: Why is a mole 6.02214076x(10 to the power 23)?

Q: Who's given the mole concept?