Question

Calculate number of molecules of sulphur S8 in 32 gm of solid sulphur.

Answer 1

Atomic mass of sulpur(S) = 32 u

Molar mass of sulphur = (S8) = 32*8 = 256 g/mol.

Now,

No. of moles = Given mass / Molar mass

No. of moles = 0.125 moles

1 mole of  sulphur contains 6.023 × 10²³ molecules.

0.125 moles of sulphur contains 0.125 * 6.023 × 10²³ molecules

i.e, 0.125 moles of sulphur contains 7.52 * 10²² molecules.