Question

0.524 gram of a substance on combustion gave 0.722 g of co2 and 0.294 g of h2o. what is the emperical formula of the substance

Answer 1

The empirical formula of the substance is CH₂

Explanation:

The substance that combustion gave is hydrocarbon which contains carbon and hydrogen.

Moles of water:

⇒ 0.294/18 = 0.0163 moles of H₂O

Moles of carbon dioxide:

⇒ 0.722/44 = 0.0164 moles of CO₂

A water contains 2 moles of hydrogen and 1 mole of oxygen.

0.0163 moles of H₂O × 2 moles of hydrogen = 0.0326 moles of hydrogen

A carbon dioxide contains 1 mole of carbon and 2 mole of oxygen.

0.0164 moles of CO₂ × 1 moles of carbon = 0.0164 moles of carbon

Now, the mole ratio is given as:

C ⇒ 0.0164 moles/0.0164 moles = 1

H ⇒ 0.0326 moles/0.0164 moles = 1.98 ≈ 2

Thus, the empirical formula of hydrocarbon is C₁H₂ = CH₂