A hydrocarbon has an empirical formula of #CH_2#, and a molecular mass of #42gmol^-1#. What is the hydrocarbon?

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Answer 1 · 2017-09-18T19:17:04

Well we got propylene or cyclopropane.....i.e. #C_3H_6#....

The molecular formula is always a whole number multiple of the empirical formula....

And thus ...........

#underbrace(12.01*g*mol^-1+2xx1.01*g*mol^-1)_"empirical formula"xxn=underbrace(42*g*mol^-1)_"molecular mass"#

And so #n=(42.0*g*mol^-1)/(12.01*g*mol^-1+2xx1.01*g*mol^-1)=3#

And so the molecular formula is #3xxCH_2-=C_3H_6#....and this is either propylene, #H_3C-CH=CH_2# or #"cyclopropane"#.

A hydrocarbon has an empirical formula of #CH_2#, and a molecular mass of #42*g*mol^-1#. What is the hydrocarbon?