Final answer:
The molecular formula of humulene is C15H24, determined by considering the amount of hydrogen added during the hydrogenation process to yield the fully saturated monocyclic hydrocarbon C15H30.
Step-by-step explanation:
The student is asking for the molecular formula of humulene. Humulene reacts with hydrogen gas in the presence of a platinum catalyst, and from the reaction details given, we know that 0.25 mol of humulene reacts with 0.75 mol of hydrogen gas to form a monocyclic hydrocarbon with the formula C15H30.
To find the molecular formula of humulene, we can start by considering that the monocyclic hydrocarbon product is fully saturated. Since 0.75 mol of H2 is used, that would mean humulene gains 0.75 * 2 = 1.5 mol of hydrogen atoms in the hydrogenation process. Therefore, the molecular formula of humulene must be C15H24 (since C15H30 - 1.5 mol of H gives C15H24).
From the balanced chemical equation, we can see that for every 1 mol of humulene, 3 mol of hydrogen gas reacts. Therefore, the ratio of moles of hydrogen to moles of humulene is 3:1. Given that 0.75 mol of H2 reacted, the moles of humulene must be 0.25 mol. Since the molecular formula of the hydrocarbon product is C15H30, we can conclude that the molecular formula of humulene is C5H10.