Posted by Christina on .
A 2.52g sample of a compound containing only carbon, hydrogen, nitrogen, oxygen, and sulfur was burned in excess O to yield 4.36g of CO2 and 0.892g of H20. Another sample of the same compound of mass 4.14g, yielded g of SO3. A third sample, of mass, 5.66g, yielded 2.80 g of HNO3. Calculate the empirical formula of the compound. Express in a chemical formula of CHSNO.
Here is how you do the 2.52g sample.
Calculate %C and %H.
4.36 g CO2 x (atomic mass C/molar mass CO2) = g C
(g C/g sample)*100 = %C
Do H the same way.
Make a new calculation for S and N. Note you have no mass for SO3.
Make a new calculation for N.
%C,H, S, O, and N should add to 100%; therefore, 100%-(%C + %H + %S + %N) = %O
Now take 100 g sample which will give you the percents as grams. Convert grams to moles of each by dividing by the atomic mass of each element. Then find the ratio of each element to each other in small whole numbers. The easy way to do that is to divide the smallest number by itself; then divide all of the other numbers by itself and round to whole numbers if necessary. DON'T round anything over 0.15. Post your work if you get stuck.