Hydrocarbons enthalpy of formation

What about the remaining comparisons mentioned above Let us recast the numbers to read that methylation decreases the enthalpy of formation of ethylene by (52.5 0.4)- (20.0 0.8) = (32.5 0.9) kJmoT1 and of cyclopropane by (53.3 0.6)-24.3 = [29.0 ( > 0.6)] kJmoT1. Let us calibrate our thinking by looking at other hydrocarbon enthalpy of formation changes upon methylation. These additional numbers for comparison are the methylation enthalpy changes of... 

Effect of hydrocarbon enthalpy of formation and hydrogen to carbon ratio on performance with liquid oxygen as rocket propellants (sea level specific impulse, Pc = 1000 psia, equilibrium expansion, mixture ratio of maximum specific impulse). 

Table V. G. 2 - Effect of Hydrocarbon Enthalpy of Formation and Hydrogen to...

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