Question

. 10ml of a gaseous hydrocarbon is mixed with
excess of oxygen and burnt. The gases are
then cooled back. The reduction in volume
was 25ml. When the gases are passed into
caustic potash, there is a further reduction
in volume of 30 ml. If all volumes are
measured under the laboratory conditions,
the hydrocarbon is
1) CH 2) CH 3) CH. 4) CHE​

Answer 1

C₃H₆ (Propene)

Step by step Solution:

♦ 10 mL of Hydrocarbon is burnt with some random amount of Oxygen.

♦ On cooling some amount of volume is reduced which is given here as 25 mL.

♦ During combustion, the gas produced is Carbon Dioxide which can be absorbeyby caustic potash reducing volume by 30 mL.

→ Moles of CO₂ = 10x = 30

→ x = 3 moles of CO₂

→ Reduction in Volume (Cooling)

→ 10(1 + y/4) = 25 mL

→ (y + 4)/4 = 25/10

→ y + 4 = 25/10 × 4

→ y = 6 moles of H₂O

Formula of Hydrocarbon = CₓHᵧ

Formula of Hydrocarbon = C₃H₆

Hence answer is C₃H₆