Empirical and Molecular Formula

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An unknown compound is analyzed and found to contain 24.3% carbon, 4.1% hydrogen, and 71.6% chlorine. If the molecular mass of the compound is 98.8g/mol, what is the compounds empirical formula and molecular formula?

24.3g C

4.1g H

71.6g Cl

24.3g C x 1 mol/12.01g = 2.02

4.1g H x 1 mol/1.01g = 4.06

71.6g Cl x 1 mol/35.45g = 2.02

24.3g C x 1 mol/12.01g = 2.02/2.02 = 1

4.1g H x 1 mol/1.01g = 4.06/2.02 = 2

71.6g Cl x 1 mol/35.45g = 2.02/2.02 = 1

24.3g C x 1 mol/12.01g = 2.02/2.02 = 1

4.1g H x 1 mol/1.01g = 4.06/2.02 = 2

71.6g Cl x 1 mol/35.45g = 2.02/2.02 = 1

C₁H₂Cl_{1 -->} CH₂Cl is the empirical formula (Ef)

CH₂Cl

C - 1 x 12.01 amu = 12.01

H - 2 x 1.01 amu = 2.02

Cl- 1 x 35.45 amu = 35.45

__________________

49.48 amu

98.8 amu/49.48 amu = 2

(CH₂Cl)2 = C₂H₄Cl_{2 is the molecular formula (Mf)}

Naphthalene, commonly known as moth balls, is composed of 93.7% carbon and 6.3% hydrogen. The molecular mass is 128g/mol. Determine the empirical and molecular formulas for naphthalene.

Ef = C₅H₄

Mf = C₁₀H₈