Question

find the number of moles of following 9 gram of H2O molecules

Answer 1

1) No. of molecules in 9g of water:

Molecular mass of water(H2O)= (1×2)+16=18g/mol

1 mole of water=18g of water contains=6.022×1023 molecules of water

then 9g of water will have= (6.022×1023/18)×9 = 3.011×1023 molecules

Answer 2

The weight of H2O molecule= 2+16= 18g per mole

Now amount of H2O = 9 gm

Number of moles = weight/ Molecular weight
= 9/18 = 0.5 Moles of H2O


Hope this helps.