The protonproton cycle thought to occur in the sun

Chapter , Problem 38

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The protonproton cycle thought to occur in the sun consists of the following sequence of reactions: (1) 1 1H 1 1 1H 2 1H 1 0 1e 1 n (2) 1 1H 1 2 1H 3 2He 1 g (3) 3 2He 1 3 2He 4 2He 1 1 1H 1 1 1H In these reactions 0 1 e is a positron (mass 5 0.000 549 u), n is a neutrino (mass < 0 u), and g is a gamma ray photon (mass 5 0 u). Note that reaction (3) uses two 3 2He nuclei, which are formed by two reactions of type (1) and two reactions of type (2). Verify that the protonproton cycle gen- * * * ** erates about 25 MeV of energy. The atomic masses are 1 1H (1.007 825 u), 2 1H (2.014 102 u), 3 2He (3.016 030 u), and 4 2He (4.002 603 u). Be sure to account for the fact that there are two electrons in two hydrogen atoms, whereas there is one electron in a single deuterium ( 2 1H) atom. The mass of one electron is 0.000 549 u.