An enzyme catalyzes the conversion of substrate $\text{A}$ into product $\text{B}.$ The rate equation for this reaction is

$-r_{A}= \dfrac{\text{C}_{A}}{5+C_{A}} \text{mol} \; \text{L}^{-1} \text{min}^{-1}$

Substrate $\text{A}$ at an initial concentration of $10 \; \text{mol L}^{-1}$ enters an ideal mixed flow reactor $(\text{MFR})$ at a flow rate of $10 \; \text{L min}^{-1}.$ The volume of the $\text{MFR}$ required for $50\%$ conversion of substrate to product is __________ $\text{L}.$