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Percent by mass C = 40.60%

Percent by mass H = 5.18%

Percent by mass O = 54.22%

Empirical formula = ? (unknown)

Inverse molar mass C = 1 mol/12.01 g

Inverse molar mass H = 1 mol/1.008 g

Inverse molar mass O = 1 mol/16.00 g

Convert the masses to moles.

C = 40.60 g/12.01 g/mol = 3.380 mol

H = 5.18 g/1.008 g/mol = 5.138 mol

O = 54.22 g/16.00 g/mol = 3.388 mol

Divide by the lowest, seeking the smallest whole-number ratio

C = 3.380/3.380 = 1 = 1 mol C

H = 5.138/3.380 = 1.52 = 1.5 mol H

O = 3.388/3.380 = 1.00 = 1 mol O

The simplest mole ratio is (1 mol C):(1.5 mol H):(1 mol O).

2 x 1 mol C = 2 mol C

2 x 1.5 mol H = 3 mol H

2 x 1 mol O = 2 mol O

The simplest whole-number ratio of atoms is (2 atoms C):(3 atoms H):(2 atoms O). The empirical formula of succinic acid is C2H3O2.

Percent by mass C = 40.60%

Percent by mass H = 5.18%

Percent by mass O = 54.22%

Empirical formula = ? (unknown)

Inverse molar mass C = 1 mol/12.01 g

Inverse molar mass H = 1 mol/1.008 g

Inverse molar mass O = 1 mol/16.00 g

Convert the masses to moles.

C = 40.60 g/12.01 g/mol = 3.380 mol

H = 5.18 g/1.008 g/mol = 5.138 mol

O = 54.22 g/16.00 g/mol = 3.388 mol

Divide by the lowest, seeking the smallest whole-number ratio

C = 3.380/3.380 = 1 = 1 mol C

H = 5.138/3.380 = 1.52 = 1.5 mol H

O = 3.388/3.380 = 1.00 = 1 mol O

The simplest mole ratio is (1 mol C):(1.5 mol H):(1 mol O).

2 x 1 mol C = 2 mol C

2 x 1.5 mol H = 3 mol H

2 x 1 mol O = 2 mol O

The simplest whole-number ratio of atoms is (2 atoms C):(3 atoms H):(2 atoms O). The empirical formula of succinic acid is C2H3O2.