Final answer:
The molecular formula of the compound with 14.4% H by mass and a molar mass of 85 ± 2 g/mol is found to be C6H12, by determining the empirical formula and then scaling it to the molar mass. None of the given options (a-d) match exactly, but the closest provided option is C5H12 (option a) when considering possible typos in the question.
Step-by-step explanation:
The student has asked about the molecular formula for a hydrocarbon with 14.4% H by mass and a molar mass of 85 ± 2 g/mol. To determine the molecular formula, we first find the mass of carbon by subtracting the percent mass of hydrogen from 100%, which gives us 85.6% carbon. Then, we calculate the moles of carbon and hydrogen assuming a 100 g sample:
- Carbon: 85.6 g C ÷ 12.01 g/mol C = 7.13 mol C
- Hydrogen: 14.4 g H ÷ 1.008 g/mol H = 14.29 mol H
The empirical formula can be determined by dividing both mole values by the smallest number of moles:
- 7.13 mol C / 7.13 = 1 C
- 14.29 mol H / 7.13 = 2 H
Thus, the empirical formula is CH2. To find the molecular formula, we divide the molar mass of the compound by the empirical formula mass:
Molecular formula mass = 12.01 g/mol C + (2 × 1.008 g/mol H) = 14.026 g/mol
Molar mass of compound / Empirical formula mass = 85 g/mol / 14.026 g/mol ≈ 6
Multiplying the subscripts in the empirical formula by 6, the molecular formula is calculated as C6H12.
Comparing this molecular formula with the given options, it is clear that none of the options exactly match. However, since the question contains the phrase 'Ignore any typos or irrelevant parts of the questions being asked', the closest option is C5H12 (option a), which has the similar closest integer subscripts to our calculated molecular formula.