The homogeneous, reversible exothermic, liquid-phase reaction A ↔ R is being carried out in a reactor system consisting of two ideal CSTRs in series. Both reactors operate at 150°C. The molar flow rate of A entering the first CSTR is 55,000 mol/h, the concentration of A in this stream is 6.5 M, and the concentration of R is zero. The fractional conversion of A in the outlet stream from the second CSTR is 0.75. The reaction is first order in both directions. The rate constant for the forward reaction at 150°C is 1.28 h-1 and the equilibrium constant based on concentration at 150°C is 10.0. If the volume of the second CSTR is 10,000 L, what is the required volume of the first CSTR?