Question

A compound contains 12.8% C, 2.1% H, and 85.1% Br (by mass). Calculate the empirical formula and the molecular formula of this compound, given that the molar mass is 188 g/mol.

Answer 1

A compound contains 12.8% C, 2.1% H, and 85.1% Br (by mass). Calculate the empirical formula and the molecular formula of this compound, given that the molar mass is 188 g/mol.

Step-by-step explanation:

Answer 2

The answer to your question is Molecular formula C₂H₄Br₂

Empirical formula CH₂Br

Step-by-step explanation:

Data

Carbon 12.8%

Hydrogen 2.1%

Bromine 85.1%

Empirical formula = ?

Molecular formula = 188 g/mol

Process

1.- Convert the percents to grams

Carbon 12.8 g

Hydrogen 2.1 g

Bromine 85.1 g

2.- Convert the grams to moles

Carbon

12 g ----------------- 1 mol

12.8 g -------------- x

x = (12.8 x 1) / 12

x = 1.07 mol

Hydrogen

1 g ------------------ 1 mol

2.1 g --------------- x

x = (2.1 x 1)/1

x = 2.1 mol

Bromine

80 g ---------------- 1 mol

85.1 g -------------- x

x = (85.1 x 1)/80

x = 1.06

3.- Divide by the lowest number of moles

Carbon 1,07/1.06 = 1

Hydrogen 2.1/1.06 = 1.99 = 2

Bromine 1.06/1.06 = 1

4.- Write the empirical formula

CH₂Br

5.- Write the molecular formula

Calculate the molar mass of the empirical formula

CH₂Br = 12 + 2 + 80 = 94

Divide the molar mass by the molar mass of the empirical formula

188/94 = 2

Multiply the empirical formula by two

C₂H₄Br₂