The halogenation of propane discloses an interesting feature of these reactions. All the hydrogens in a complex alkane do not exhibit equal reactivity. For example, propane has eight hydrogens, six of them being structurally equivalent primary, and the other two being secondary
100.3kcal of heat will be absorbed.
2moles of NO absorb 43kcal.
I mole of NO weighs 14 +16 = 30g so 2 moles weigh 60g.
So 60g absorb 43kcal
So 1g absorb 43/60 kcal
So 136g absorb (43/60) x 136 = 97.47 kcal
