A well-stirred tank of volume V= 2m^3 is filled with brine, in which the initial concentration of NaCl at t=0 s is Co=1 kg/m^3. Subsequently, a flow rate of Q = 0.01 m^3/S of pure water is fed steadily to the tank, and a flow rate of brine at V=0.03 m^3/s leaves the tank through a drain. Derive an expression for the subsequent concentration of NaCl (C) in terms of Co, t, Q, and V. How long will it take for the concentration of sodium chloride take to fall to a final value of 0.0005 kg/m^3?