Question

Question 10 Calculate the number of molecules of sulphur (S8) present in 16 g of solid sulphur.

Class 9 - Science - Atoms and Molecules Page 44

Answer 1

Heya !

Here is your answer ==============================================================================

>> The molecules formula of sulphur is given to be S8 ( it Contains 8 atoms of sulphur ). So , the molecular mass of sulphur molecule is 32 × 8 = 256 u. This means that 1 mole of sulphur molecules is equal to 256 grams.

Now, 256 g of sulphur = 1 mole of sulphur molecules

So, 16 g of sulphur = 1/ 256 × 16 mole of sulphur molecules

= 0.0625 mole of sulphur molecules

Also, 1 mole of sulphur molecules = 6.023 × 10²³ molecules

So, 0.0625 mole of sulphur molecules = 6.025 × 10²³ × 0.0625 molecules

= 3.76 × 10²² molecules

Hope it helps !!!

Answer 2

HI !

Molecular mass of Sulphur (S) = 32 x 8 = 256 g

Given mass = 16 g

No: of moles = Given mass / Molar mass
= 16/256 moles

No: of molecules = No: of moles x Avogadro no:
= 16/256 x 6.022 x 10²³ molecules