Question

a compound has the empirical formula c₂h₄s. its molecular weight is 120 g/mol. identify the molecular formula of the compound. a) c₂h₄s b) c₃h₂0s₂ c) c₄h8s₂ d) c₄h8s₃ ₁ e) c₆h₁₆s

Answer 1

C4H8S2, Option C

Step-by-step explanation:

Clarification on the question: A molecular weight of 120 means a molar mass of 120 g/mol. Molecular weight does not have units of grams/mole. Molar mass does. We will assume that the phrase "molecular weight is 120 g/mol" should read "molar weight is 120 g/mol."

The first step is to determine the molar mass of C2H4S. If it is 120 g/mol, the the molecular formula is indeed C2H4S.

Molar Mass C2H4S

2 C at 12/C = 24

4 H at 1/H = 4

1 S at 32/S = 32

Molar mass = 60 g/mol

This is 1/2 the molar mass of the compound in question.

The compound has a molar mass of 120 g/mole, so if we double the atoms of each element, it will be 120 grams/mole.

The compound becomes C4H8S2, Option C.