Question

Convert the following into mole:-
a) 12 gram of oxygen gas (0=16)

b) 20 gram of water (1=16)

Answer 1

a) mole = weight given / molar weight

= 12/16

=3/4

= 0.8

b) mole = 20/18

= 1.11

(molar weight of water is 18 not 16

Answer 2

a)1 mol O is 16 gm as its atomic weight is 16u

therefore 12gm is 12/16 mol

i.e.(0.75 OR 3/4)mole

-

-

b)18gm water makes 1 mole of water as its molecular weight is 18u

therefore 20 grams will make 20/18 moles of water molecules

i.e. (10/9 OR 1.11111....OR approx. 1.11112)mole