The value relates to the enthalpy of a chemical reaction or the energy of radioactive decay products.
enables the general definition of Q based on the mass–energy equivalence.
of the nuclear species as: Chemical Q values are measurement in calorimetry.
Exothermic chemical reactions tend to be more spontaneous and can emit light or heat, resulting in runaway feedback(i.e. explosions).
For example, Sargent's rule states that weak reaction rates are proportional to Q5.
The Q value is the kinetic energy released in the decay at rest.
The neutron has no initial kinetic energy since it is at rest.
Experiments are studying emission spectrums to search for neutrinoless decay and neutrino mass; this is the principle of the ongoing KATRIN experiment.