(Hydrogen burning into helium)
Inside stars four protons eventually combine, through a sequence of reactions, into one helium-4 nucleus. Neglect the tiny masses of the emitted positrons and neutrinos and treat the process schematically as
4 11H → 24He
The relevant atomic masses are:
• proton = 1.007276 u • 4He = 4.002603 u
Constants: 1 u = 931.5 MeV, 1 eV = 1.60 × 10⁻¹⁹ J, NA = 6.022 × 10²³ mol⁻¹.
Answer the following:
(i) Calculate the mass defect for the conversion of four protons into one helium-4 nucleus in atomic mass units.
(ii) Determine the energy released per such conversion in MeV.
(iii) Estimate the total energy, in joules, produced when 1.0 kg of hydrogen is completely converted into helium by this process.