Question

The volatile liquid ethyl mercaptan, C₂H₆S, is one of the most odoriferous substances known. It is sometimes added to natural gas to make gas leaks detectable. How many C₂H₆S molecules are contained in a 1.0 mL sample? The density of liquid ethyl mercaptan is 0.84 g/mL.

Answer 1

Mass in 1ml= $density \times volume=0.84\times 1 = 0.84g$

Molar mass of $C_2H_6S=(12.011\times 2+1.008\times 6+32.06\times 1)g/mol$

Moles of $C_2H_6S=mass /molar mass=0.84/62.134=0.0135moles$

Since, 1 mole molecules contain $6.022\times 10^{23}molecules$

number of molecules present in 0.0135 moles $=0.0135\times 6.022\times 10^{23}=8.13\times 10^{21}molecules$