Question

A 4.70 g of a C.H. compound was combusted in air to make 15.3 g of CO, and 4.70 g H.O. What is the empirical formula? Balance the chemical equation.

Answer 1

The empirical formula is C₂H₃

Step-by-step explanation:

The empirical formula of a chemical compound is defined as the simplest positive integer ratio of atoms present in a compound.

The reaction of combustion for a CₐHₓ is:

CₐHₓ + (a+x/4) O₂ → a CO₂ + ˣ/₂ H₂O

The moles obtained are

15,3 g of CO₂ ×
`(1mol)/(44,01g)` = 0,3476 moles of CO₂≡moles of C

4,70 g of H₂O ×
`(1mol)/(18,02g)` = 0,2608 moles of H₂O × 2 = 0,5216 moles of H.

The ratio H:C is 0,5216/0,3476= 1,5. That means you have 1,5 H per 1C, that is the same than 3H per 2C. Thus, empirical formula is:

C₂H₃

I hope it helps!