Why is the Q value for symmetric U236 fission lower than asymmetric fission?

[matt222]

I have question regarding the fission of 236U,my question is why we have the Q value (185MeV) of the symmetric fission of U236 (two 118Ru) is less than the Q value (188MeV) for the fission into 96Sr and 140Xe

 

[RocketSci5KN]

Less mass was converted to energy.