molecular formula: a whole-number multiple of an empirical formula… …showing the total number of each atom in a molecule formaldehyde CH 2 O acetic acid C 2 H 4 O 2 glucose C 6 H 12 O 6 all same empirical formula: (same ratio of atoms) CH 2 O

Calculate the molecular formula of a compound with the empirical formula CH 4 N and a molar mass of 60.0 g/mol. molecular mass = multiple of emp. form. empirical mass 1(C) + 4(H) + 1(N) = (1.01) = g/mol 60.0 = ≈ 22 (CH 4 N) = C2H8N2C2H8N2 multiple of emp. form.

Calculate the molecular formula of benzene with the empirical formula CH and a molar mass of 78 g/mol. empirical mass 1(C) + 1(H) = = g/mol 78 = ≈ 66 (CH) = C6H6C6H6 molecular mass = multiple of emp. form. empirical mass multiple of emp. form.

1. True or False: A molecular formula can be the same as an empirical formula. Example: Formaldehyde has the empirical formula CH 2 O, which is the formula of the actual molecule. Quick Quiz.

2. Determine the molecular formula of a compound with 40.0 % C, 6.70 % H, and 53.3 % O by mass that has a molecular mass of 60 g/mol. A.C 2 H 4 O 2 B.CH 2 O C.C 2 H 3 O D.C 2 H 4 O Quick Quiz g C 6.70 g H 53.3 g O 3.33 mol C 6.63 mol H 3.33 mol O ________ 3.33 _________ 3.33 ________ 3.33 = 1 C = 2 H = 1 O CH 2 O = 2 2 (CH 2 O) = x 1 mol C g C x 1 mol H 1.01 g H x 1 mol O g O ======