Question $1$

Consider the mixing process taking place in a two$-$stage system as shown in Fig. $1\mathrm{.}0.$

The goal is to tightly control the exit temperature $T_5$ and concentration at the outlet of the tank $2.$ The major disturbances are the stream temperatures and composition, including the steam temperature.

Assuming that the heats of solution weakly depends the concentrations and can be neglected, and that the hold$-$up for each tank is constant.

a$)$ Identify the state variables of the system.

b$)$ State the balances that should be performed to determine completely the dynamic behaviour of the system.