Question

A hydrocarbon contains 7.70% hydrogen and 0.56 L of the hydrocarbon weigh 1.95 g at STP.
Then the atomicity of hydrocarbon is

Answer 1

The molecule has 6 carbon and 6 hydrogen atoms.

Explanation:

1 mole of gas occupies 22.4 lt.

x mole of gas will occupy 0.56 lt

 1/x = 22.4 / 0.56

  1/x = 40

 so x = 1/40 = 0.025

 0.025 mole has mass 1.95 g

1 mole has mass = 1.95 / 0.025 = 78 g

Molar mass of the diacarben = 78 g

7.70% of 78 = 7.70 / 100 * 78 = 6

So 6 H atoms.

No of C atoms = 72/ 12 = 6

So the molecule has 6 carbon and 6 hydrogen atoms.

C6H6 or Benzene is the molecule.