Question

how to convert grams into moles

Answer 1

this is understood by given one example . let 20 gram of Ca given
then ask how many no of mole of 20gm calcium .
then you use formula ,
mole = given weight /molecular weight
we know molecular weight 40 gm
now,
mole =20 gm /40 gm
=1/2 =0.5
hence 20gm calcium means 0.5 mole of calcium .
I hope you understood

Answer 2

First of all there is a limitations u can't covert grams into moles until and unless u know its molar mass
So for better clarification let us take an example of very common compound yet essential H20 , 36 gm of water is given to u and u have been asked to calculate how many moles it contains
So we know that formula
No of moles =Mass given/ Molar mass
Here
No of moles will be 36/18
==> 2 moles
Now u can tell the teacher that it contains 2 moles