Question

mixture of 75 cm3of oxygen and 12.5 cm3 of a gaseous hydrocarbon H were exploded in an eudiometer. After cooling to room temperature, 50 cm3 of gas was left and when this was shaken with KOH solution, 12.5 cm3 of oxygen remained. Given that all the volumes were measured at same temperature and pressure, calculate the molar mass of the hydrocarbon H.

Answer 1

molar mass of C₃H ₈ = 44 g/mole

Step-by-step explanation:

Computation of the amount of oxygen that reacts .

⇒ 75 - 12.5

⇒ 62.5 cm³

Computation of proportion of hydrocarbons

2 mole hydrocarbons 3n+1 oxygen

⇒ 3 n + 1 = [62.5 × 2] / 12.5

⇒ 3 n + 1 = 10

⇒ n = 3

So,

Formula of the hydrocarbon is C₃H ₈

Computation of molar mass of C₃H ₈

⇒ [12×3] + [1×8]

⇒ 44 g/mole