Question

Write the reaction equation for electron capture on a potassium-40 nucleus and calculate the reaction energy.

Answer 1

The equation is

$$^{40}_{19}\text{K}+e^-→^{40}_{18}\text{Ar}.$$

The energy* is

$$E=\Delta mc^2=1.873\text{ MeV}.$$

*Ar-40 is 39.962 amu,

K-40 is 39.964008 amu.