Qualitive analysis is about determining the components of a mixture, compound etc or the appearance or characteristics of it. U can talk about that experiment and describe the difference in soot production between the alkanols. i.e: methanol had less than ethanol and less than propanol etc... this is qualitive analysis.
for quantitive analysis whic involves measuring how much of each component there is etc,, talk about the difference in molar hear of combustion between the alkanols
i think this will be an excellent approach.