Question

calculate the number of molecules in 64 g of sulphur molecule

Answer 1

64g of S
Molecular Mass of Sulphur = 32g/mol 

64g of S/ 32 g/mol  = 2 mol 

1 mol = 6.022 x 1023 atoms

2 mol  *  6.022 x 1023

         =1.2044 x 1024 atoms of S

1 molecule of S = 8 atoms

1.2044 x 1024 /8 = 1.5055 x 1023 molecules of S

Answer 2

Dear student!

Given that, atomic mass of S-atom = 32u , given mass of S8 molecule= 64 gm

so, molecular mass of S8 molecule = 32 x 8 =256u = 256 gm

Hence , molar mass of S8 molecule= 256 gm

No. of molecules = no. of moles x Avogadro's number

Since no. of moles = given mass / molar mass

So, No. of moles of sulphur = 64/256= 0.25 mol

Thus, no. of molecules of sulphur = 0.24 x 6.022 x 1023 = 1.50 x 1023