# Mole concept

Friday, September 23 2011 | 8:00 PM (IST)

The class is over

Duration:
90 minutes
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Theory and problems of mole concept will be discussed. Useful to students studying chemistry in GCSE - O/A level, IIT-JEE/AIEEE preparatory level , CBSE and any State of Indian board of syllabus.
Mole Concept

Concept – 1 - Mole

One mole of any substance contains
602,200,000,000,000,000,000,000 molecules.
represented by 6.022 x 10^23

What is a mole?
A unit which has a mass equal to the relative atomic mass or relative molecular mass or formula mass.

A simple equation:

n = w/A or w/M

where
n = number of moles of the given substance or element
w = mass of the given substance
A = relative atomic mass of the element
M = relative molecular mass of the substance

Problems:
Calculate the mole of the substances given below.
(a) 16 g of O2 and 14 g of N2
(b) 8 g of O2 and 22 g of CO2
(c) 28 g of N2 and 22 g of CO2
(d) 32 g of O2 and 32 g of N2

Concept – 2 – Number of molecules / atoms
Based on Avogadro’s number we can count the number of molecules present in a given mass of a substance.

n’ = N x n
where
n’ = number of molecules or atoms
n = mole

Problems:
Calculate the number of molecules of carbon dioxide in 440 g carbon dioxide gas at S.T.P.

Language of instruction: English

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Attendees in the class (6)