Question

How to understand mole easily

Answer 1

Answer:

mole is nothing but a unit to measure amount of substance.

and in chemistry one mole of any compound or element is equal to the value of gm equivalent weight.

gram equivalent weight is the value simply to understand like it is just the molecular mass expressed as unit gm instead of amu.

Explanation:

for example we can take Na₂CO₃(sodium bicarbonate):

molecular mass of sodium carbonate is :

= 2*( atomic mass of Na)+atomic mass of C + 3* (atomic mass of O)

=2*23+12+3*16

=46+12+48

=96 amu

∴ gram equivalent weight = 96 gm

similarly,

that of chlorine is 35.5 gm

and goes on.

Answer 2

• You are aware of the measure words dozen, pair, right?Just like that mole is a measure word of mentioning no. of atoms

• If you take a molecule of an element you will be having billions of atoms in it which is nearly impossible to write  all that all the time during calculations. So for our  ease to do calculations we convert the very large numbers(no. of atoms) into a smaller quantity called moles

• 1 mole of a substance = molecular mass = 6.022* 10 ^23 atoms = 22.4l at STP

• Always remember this when calculating moles

• Let me take some examples to explain this,

If you take 1 mole of Sodium in a container and weigh it, you will be always getting the same value that is 23 u( molecular mass of sodium)

likewise, 1 mole of aluminium always weigh 27g  and so on

• So, we can say 1 mole = molecular mass of substance

If you take 1 mole of sodium and count the no.of atoms in it , at any cases you will be getting only 6.022 * 10^23 atoms

same  if you take 35.5 g of Chlorine or 1 mole of Cl you will only be getting 6.022*10^23 atoms and so on

• So we can also say 1 mole of a substance has 6.022*10^23 atoms ALWAYS

• If you take 1 mole of Oxygen(or any gas) and find the volume occupied by it, you will always find the volume to be 22.4L at STP only(Standard temperature and Pressure. Std temp = 0°C & std pressure = 760mm of Hg)

Like wise if you take 1u of Hydrogen it will always occupy  22.4L and so on

• 1mole of a substance = 22.4l of volume at STP

At first mole concept might sound confusing but with daily practise you can do these problems with no effort!

Hope it is clear!