Answer:
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.
Explanation:
Answer:
The answer to your question is Molecular formula C₂H₄Br₂
Empirical formula CH₂Br
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
