Calculating an Empirical Formula Ascorbic acid (vitamin C) contains 40.92% C, 4.58% H, and 54.50% 0 by mass. What is the empirical formula of ascorbic acid? A 5.325-g sample of methyl benzoate, a compound used in the manufacture of perfumes, contains 3.758 g of carbon, 0.316 g of hydrogen, and 1.251 g of oxygen. What is the empirical formula of this substance?
Solution 2PE Step 1 Empirical formula :Empirical formula" is a REAL IMPORTANT concept. Here's the definition: the formula of a compound expressed as the smallest possible whole-number ratio of subscripts of the elements in the formula For example, CH COOH has two carbons, four hydrogens and two oxygens. So we could write 3 the formula like this: C242nd so it reduces to CH O2 below describes the steps involved in calculating an empirical formula. the method for converting percentage composition to an empirical formula. Percent to mass. Mass to mole. Divide by small. Multiply 'til whole. Step 2 Per cent to mass: Ascorbic acid (vitamin C) contains 40.92% C, 4.58% H, and 54.50% 0 by mass. Carbon =40.92%.=40.92g Hydrogen =4.58%=4.58g Oxygen =54.50%=54.50g. Step 3 Mass to mole : Carbon =40.92 g of C*1 mol of C/12.2g of C=3.35moles. Hydrogen =4.58 g of H*1 mol of H/1.008 g of H=4.54moles . Oxygen =54.50 of O*1 mol of O/16.0g of O=3.40 moles . Step4 Divide by small: Determine mole ratios by dividing the moles for each element by the smallest number of moles. C: 3.407mol/3.406mol=1.000 H: 4.54mol/3.406mol=1.33 H: 3.406mol/3.406mol=1.000