Example 9.4. An agitated vessel 6 ft (1.83 m) in diameter contains a six-blade straight-blade turbine 2 Rt (0.61 m) in diameter, set one impeller diameter above the vessel floor, and rotating at 80 r/min. It is proposed to use this vessel for neutralizing a dilute aqueous solution of NaOH at 70F with a stoichiometrically cquivalent quantity of concentrated nitric acid (HNO3). The final depth of liquid in the vessel is to be 6 (1.83 m). Assuming that all the acid is added to the vessel at one time, how long will it take for the neutralization to be complete