Final answer:
The molecular formula of a compound with a carbon to hydrogen mole ratio of 1:2 and a molecular weight of 42 g/mol is C3H6.
Step-by-step explanation:
To determine the molecular formula of a compound containing carbon and hydrogen with a mole ratio of 1 to 2 and a molecular weight of 42, we start by considering the atomic masses of carbon and hydrogen. The atomic mass of carbon (C) is approximately 12 g/mol, and that of hydrogen (H) is about 1 g/mol. Since the mole ratio is 1:2 for C to H, the simplest formula could be CH2.
Next, we calculate the molecular weight of this simplest formula: (12 g/mol for C) + (2 g/mol for H) = 14 g/mol for CH2. To find the multiplier to reach the compound's molecular weight of 42 g/mol, we divide 42 by 14, which is 3. This means the molecular formula is 3 times the mass of the empirical formula.
Therefore, the molecular formula of the compound is C3H6.