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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: atomazing on September 17, 2005, 06:12:08 PM

Title: Find the empirical formula of unknown compound.
Post by: atomazing on September 17, 2005, 06:12:08 PM

A compound contains only C, H, and N. Combustion of 38.2 mg of the compound produces 36.5 mg CO2 and 44.8 mg H2O. What is the empirical formula of the compound?


I have attempted this many times and do not understand how the compound can contain only C, H, and N, and not have any N in the resulting products? I have calculated the moles of Co2 and H2O but don't understand how this converts to the unknown compound.

Title: Re:Find the empirical formula of unknown compound.
Post by: Borek on September 17, 2005, 06:38:19 PM

You have to find out amount of carbon and hydrogen in the sample - what is left is nitrogen. CO₂ and H₂O are easy to catch and analyze, nitrogen often ends as N₂ and as such is almost completely inert.