Practice_EXAM_I

Thatisthemolarmassempiricalmolarmassxintegerfromch8000

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Unformatted text preview: toms, C, H, Cl and O. Thus mole of C = 37.84/12 = 3.15; mole of H = 2.12/1 = 2.12; mole of Cl = 55.84/35.45 = 1.58; mole of O = 4.20/16 = 0.26. Note that as long as one of the moles is not an integer, we have to divide the smallest value among them: here the smallest value is 0.26. So C : H : Cl : O = 3.15/0.26 : 2.12/0.26 : 1.58/0.26 : 0.26/0.26 = 12.1: 8.1 : 6.1: 1 = 12: 8: 6: 1, which indicates that the empirical formula contains 12 C, 8 H, 6 Cl and 1 O. Thus, the empirical formula is written as C12H8Cl6O as 1 is usually not written in the formula. *****What is the empirical formula for methyl benzoate, a compound used in the manufacture of perfumes, contains 70.57% carbon, 5.94% hydrogen, and 23.49% oxygen? Note: subscripts must be integers. B) C2H2O0.5 C) C8H8O2 D) CHO A) C4H4O Hint: Section 9.8. This is a very, very important question. The empirical formula is the simplest integral ratio of moles among each atom. Here, there are three different kinds of atoms, C, H and O. Thus mole of C = 70.57/12 = 5.88; mole of H = 5....
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