7.4 Lesson: Combustion Analysis

Combustion Analysis

Objective: Using combustion analysis data to determine the empirical/molecular formula

What is combustion analysis?

• A method of determining the empirical/molecular formula fo an unknown by using the process of combustion and collecting and analyzing the products.

• Remember combustion reaction

  C_nH_m + O₂ → CO₂ + H₂O

• We will use stpochometric relationship to determine the amount of C and H are in the product and then solve for the empirical and then molecular formula

Steps

1) Use the amount of CO₂ prodcued to determine the amount of C was present in the sample. (mass CO₂→mol CO₂→mol C→mass C)

2) Use the amount of H₂O prodcued to determine the amount of H was present in the sample. (mass H₂O →mol H₂O →mol H→mass H)

3) If the initial compound has O in it, subtract the mass of C and H from the mass of the initial compound to get the mass of the O (mass of reactant - (Mass of C + mass H)= mass O)

4) now proceed like finding empirical/molecular formula

​A 0.2500 g sample of a compound known to contain carbon, hydrogen and oxygen undergoes complete combustion to produce 0.3664 g of CO₂ and 0.1500 g of H₂O. What is the empirical formula of this compound?