Question #2c86e

1 Answer
May 8, 2017

Answer:

The molecular formula will be #C_6H_6#; no prizes for guessing what this molecule is......

Explanation:

As with all these problems, it is useful to assume that there is a #100*g# mass of compound, and divide each elemental mass thru by the ATOMIC mass of each component.

And so..........

#"moles of carbon"-=(92.5*g)/(12.011*g*mol^-1)=7.70*mol#

#"moles of hydrogen"-=(7.50*g)/(1.00794*g*mol^-1)=7.50*mol#

And if we divide thru by the LOWEST molar quantity we gets.....and empirical formula of #CH#.

But the molecular formula is always a whole number of the empirical formula:

#"molecular formula"="empirical formula"xxn#

And so #78*g*mol^-1=nxx(12.011+1.00794)*g*mol^-1#; clearly, #n=6#, and the #"molecular formula"# is #C_6H_6#, which is what VERY common organic molecule?