What is the empirical formula of caproic acid and what is the molecular formula if the molar mass is 116 g/mol?

Question

Caproic acid, which is responsible for the foul and ripe odor of dirty socks, is composed of C, H, & O atoms. Combustion with excess oxygen of a 0.225 g sample of this compound produces 0.512 g CO2 and 0.209 g H2O. What is the empirical formula of caproic acid and what is the molecular formula if the molar mass is 116 g/mol?

Answer 1

So Abdulrahman A.,

You should know by now, first write a balanced equation for combustion, then convert any data to moles of reactant, "chase it through" the equation (by which I mean, scale all the coefficients to keep them in the balanced-equation proportion) to get product moles, convert to mass. Except -- you are doing this process in reverse in this problem, aren't you. What is the single missing datum that will enable you to convert to a balanced reaction? The mass of oxygen used, of course. And how do you find that (hint: mass is neither created nor destroyed ....) Once you have 3 of those coefficients, you'd better be able to calculate the 4th by simple arithmetic!

That should get you perking towards the solution ....

And by the way, butanoic (butyric), pentanoic (valeric), hexanoic (caproic), heptanoic (caprylic) acids are all pretty smelly. Higher than that, the volatility is getting less, so they aren't quite as obnoxious.

-- Cheers, --Mr. d.