How can I determine the molecular formula for a compound that contains only C and H and has a molecular ion with an m/z value of 72?
1 Answer
May 11, 2015
use rule of 13.

divide m/z by 13. In this situation, 72/13.
72/13 = 5 + 7/13 . 
use formula
#C_nH_(n+r)# .
where; n = 5 and r = 7.
by inserting the value of n and r into the formula, we get,#C_5H_12#