A hydrocarbon has an empirical formula of $C H_{2}$ $CH_2$ , and a molecular mass of $42 \cdot g \cdot m o l^{- 1}$ $42gmol^-1$ . What is the hydrocarbon?

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Answer 1 · 2017-09-18T19:17:04

Well we got propylene or cyclopropane.....i.e. $C_{3} H_{6}$ $C_3H_6$ ....

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_2CH2CH_2, and a molecular mass of 42*g*mol^-142⋅g⋅mol−142*g*mol^-1. What is the hydrocarbon?