Final answer:
To determine a compound's molecular formula, one starts with the empirical formula, calculates mole ratios of elements, compares the empirical and molar mass, and then adjusts the subscripts to find the molecular formula.
Step-by-step explanation:
The determination of a chemical formula, such as that by Job's method, is a fundamental aspect of analytical chemistry. To determine a compound's molecular formula, one typically starts by establishing its empirical formula. This requires measuring the masses of the constituent elements and converting those values to moles, facilitated by the known molar masses of the elements. These molar amounts help in calculating whole-number ratios and deriving the empirical formula represented as AxBy. The next step is to compare the compound's empirical formula mass to its molar mass. In practice, this might involve starting with a hypothetical 100-g sample, as often done with percent composition calculations. The molecular formula is finally obtained by determining the factor by which the subscripts in the empirical formula are to be multiplied, bridging the empirical and molecular formulas.