Question

m-32 is radioactive and decays by either beta plus or beta neutral (electron 42 sture modes. (a calculate the binding energy per nucleon for sodium-2n,sodium- caPdodium-24. (b) For the beta plus decay mode of sodium-22, write a reaction sho all of the decay products and calculate Q for the reaction. ( For the beta neutral decay mode of sodium-22, wr'ite a reaction showing all of the decay products and calculate Q for reaction. (d) What would be the decay rate for a 1.0 ng sample of sodium-22? (e) What mass of sodium-22 atoms would remain after 20 years? odium-22, write a reaction showing sodium-22 half-life 2.60 years (Z-10) (Z-11) Sodium-22 Neon-20o Neon-22 19.992440 u 21.991386u Sodium-23 Sodium-24 21.994437 u 22.98977o u 23.990963 u (Z-12) Magnesium-22 21.993267 u Magnesium-24 23.985042 u

Answer 1

BE(_z^A X) = [z m_p + (A - z)m_A - m(_z^A X)]c^2 BE(_11^22Na) = [11(1.00728) + 11(1.008664) - 21.994437]amu c^2 = (0.180947 amu)c^2 = 168.55 mtv (1 amu)c^2 = 931.5 mtv BE/N = 168.55/22 = 7.661 mtv/NUCLEOUS b)_11^22 Na rightarrow_10^22 N_p +_+ 1^0 e + v_c Q = [m(_11^22 Na) - m(_10^22 Ne) - 2 m_e]c^2 = [21.994437 - 21.991386 - 2(0.00054861]amu c^2 = 1.819 mev (c)_11^22 Na rightarrow_10^22 Ne + v_e Q = [m(_11^22 Na) - m(_10^22 Ne)]c^2 = (21.994437 - 21.991386)amu c^2 = 2.842 mev (d) DECAY RATE R = dN/dt = lambda N = ln 2/T N R = ln 2/20yrs 6.022 times 10^23/21.994 g (1.0 times 10^-3 g) = 9.489 times 10^11 DISINTEGRATION/rs = 3.009 times 10^4 DISINTEGRATION/sec (OR eq) 1 MOLE Na - 22 = 6.022 times 10^23 NUCLE 21.994 of Na - 22 = 6.022 times 10^23 NUCLE POLAR MASS OF Na - 22