Question

A sample of a compound contains 5.58 g carbon, 0.703 g hydrogen, and 3.72 g oxygen. Its molar mass is approximately 172.18 g/mol. What is the empirical formula of the compound?

a) C₃H₂O₂
b) C₄H₃O
c) C₂H₃O₂
​d) C₅H₄O

Answer 1

The empirical formula of the compound is C2H3O.

Step-by-step explanation:

To determine the empirical formula of a compound, we need to find the ratio of the elements present in the compound. The first step is to convert the given masses of carbon, hydrogen, and oxygen into moles. The molar amounts are calculated as follows:

• Carbon (C): 5.58 g / 12.01 g/mol = 0.464 mol
• Hydrogen (H): 0.703 g / 1.01 g/mol = 0.695 mol
• Oxygen (O): 3.72 g / 16.00 g/mol = 0.232 mol

Next, we need to find the simplest whole number ratio of the elements by dividing each molar amount by the smallest molar amount in order to normalize the values. Dividing by 0.232 mol gives us:

• Carbon (C): 0.464 mol / 0.232 mol = 2
• Hydrogen (H): 0.695 mol / 0.232 mol = 3
• Oxygen (O): 0.232 mol / 0.232 mol = 1

The empirical formula of the compound is C2H3O1, which can be simplified to C2H3O1 or C2H3O.