TUTOR Empirical Formulas. weight percents relative moles of

Last updated: 7/10/2022

TUTOR Empirical Formulas. weight percents relative moles of each element mole ratios of the elements empirical formula Step 1 Assume 100 g of sample. The mass percent of each element can therefore be used as a mass, in grams. Calculate the amount of C present (in moles) in the 100-g of sample. Calculate the amount of H present (in moles) in the 100-g of sample. Calculate the mass precent of O by difference. %0 = 100 (%C + %H) Use this to calculate the amount of O present (in moles) in the 100-g of sample. Step 2 Compare the amounts (in moles) of the three elements. Calculate mole ratios by dividing the amount (mol) of each by the amount (mol) of the element present in the smallest amount. Step 3 Use the mole ratios to determine the empirical formula. The relative amounts (mol) present correspond with the relative number of atoms in the formula. If the ratios are not integers, convert them into improper fractions. For example, 1.5 becomes 1 1/2 and then 3/2. Likewise, 2.33 becomes 2 1/3 and 7/3. Similarly, 1.6 would be 1 3/5, or 8/5. Then the numerators and denominators of the fractions give relative whole numbers of atoms. For example, 2 1/3 is 7/3, which gives a ratio of atoms of 7 to 3. An alcohol is 70.57 % C and 5.935 % H by mass. The rest is oxygen. What is the empirical formula of the alcohol? Enter the elements in the order C, H, and then O.