The decomposition of benzoyl peroxide is characterized by a half-life of 7.3 h at 70 °C and an activation energy of 29.7 kcal/mol. What concentration (mol/L) of this peroxide is needed to convert 50% of the original charge of a vinyl monomer to polymer in 6 hours at 60 °C, given that f = 0.4, kp2/kt = 1.04x10-2 L/mol-s at 60 °C, and the kd of the initiator can be determined from the equation t1/2 = (ln 2)/kd?