Question

I am Preparing for Engineering.
As we all know that 'Mole Concept' is most evergreen and important+Basic topic of chemistry.

Help me to understand MOLE CONCEPT to it fullest, as much required for Engineering Entrance Exam.

Answer 1

Chemistry Madam @Preetha I personally want your direction in this particular topic. I will be thankful to you.

Answer 2

Ok the Mol is a unit in chemistry. With the discovery of the staggering amount of molecules/atoms/formula units in a substance, chemists needed a way to easily identify the number of molecules in a easy and compact manner. With some statistics and looking at the broad span of molecules in different masses of different substances, Italian chemist Avogadro decided that the best and most conveinient method to represent all the molecules in a substance which would have a substantial size to be seen was by inventing the unit called a "Molecular Unit". This unit he described had represented \(6.02(10)^{23}\) Molecules of a substance and the purpose of having that number was that in general, no matter what the substance was, one mol of molecules of that substance would be reasonably easy to see. This unit is directly connected to the weight of substances. The mass of a substance is described in Atomic Mass Units (AMUs) which represents the grams of the substance in one mole!

Answer 3

How to use it in Numerical ?

Answer 4

http://crescentok.com/staff/jaskew/isr/chemistry/class13.htm

Answer 5

http://web.clark.edu/nfattaleh/classes/100/LectureNotes/Ch6.pdf

Answer 6

In general, the number of moles of a substance, \(n\), is given by:
\[n=\frac{N}{N_A}\]
Where \(N\) is the number of particles and \(N_A\) is the Avogadro constant which is \((6.02*10^{23})\).

Answer 7

As well, to find the mass, \(m\) in grams, of \(n\) moles of a substance, you use the following formula:
\[m=Mn\]
Where \(M\) is the Atomic weight of the substance in AMUs in grams/mol so lets say for water \((H_20)\), Its atomic weight is \(18.02\phantom{.}g/mol\) So the weight in grams would be
\[m=18.02n\]
If you have one mol of water, its weight would be 18.02 grams. Similarly, you can eliminate "Moles \((n)\)" from the mass equation by substituting
\[n=\frac{N}{N_A}\] and getting:
\[m=\frac{NM}{N_A}\]

Answer 8

Thank you very much @KeithAfasCalcLover and @asmagul

Answer 9

A mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon-12, where the carbon-12 atoms are unbound, at rest and in their ground state. The number of atoms in 0.012 kilogram of carbon is known as Avogadro number, and is determined empirically. The currently accepted value is
\[6.0221415 x 10^{23} mol ^{-1}\]

Complete concept of Mole is at http://goo.gl/bknwUQ