Dimethylbenzenes, or xylenes, are hydrocarbons composed of two CH3– groups bonded to a 6-carbon
ring. They have the same molecular formula, which is C8H10, and differ only in the placement of the CH3–
groups on the ring. These compounds are flammable and sometimes used as accelerants in arson fires. A
sample taken from the scene of a suspected arson fire is found to be 90.49 % carbon and 9.51 % hydrogen.
Based on the percent composition information, is it possible that the sample is a dimethylbenzene? Explain your answer.

Question

Dimethylbenzenes, or xylenes, are hydrocarbons composed of two CH3– groups bonded to a 6-carbon 
ring. They have the same molecular formula, which is C8H10, and differ only in the placement of the CH3– 
groups on the ring. These compounds are flammable and sometimes used as accelerants in arson fires. A 
sample taken from the scene of a suspected arson fire is found to be 90.49 % carbon and 9.51 % hydrogen.
Based on the percent composition information, is it possible that the sample is a dimethylbenzene? Explain your answer.

aaronq · Answer

you're essentially finding it's mass percent composition.

asib1214 · Answer

ok thanks

aaronq · Answer

no problem

aaronq · Answer

they're not asking you to determine which one it was, just to determine IF it could be dimethylbenzene.

SO find the mass percent composition of dimethylbenzene (which i think you already did) and compare it to the one they gave you. If it fits then DMB is a suspect.

asib1214 · Answer

i think DMB, Dimethylbenzene, C8H10 is the suspect... thanks pal. :)

aaronq · Answer

good stuff! no problem