The aim of this experiment is to compare the theoretical conversion for a saponification reaction to the experimentally determined conversion in a batch reactor under constant temperature conditions.
The first step was to ensure the electrical supply to the rig was turned off and that the Armfield batch reactor was empty and clean. 500mL of 0.1M sodium hydroxide solution was then added manually. The pump and stirrer were then set to 7.0 and turned on. The batch reactor was started to ensure the conductivity probe was functional and the reading was displayed on the PC. 500mL of ethyl acetate was then added to the reactor, which was maintained at approximately thirty degrees Celsius by a water bath. As soon as the ethyl acetate was added, the conductivity and temperature were measured at two minute intervals until the conductivity plateaued, indicating the point of maximum conversion for the reaction.
For the theoretical calculations, Equation 3 from the laboratory manual was used to calculate conversion. This equation is derived from the design equation of the ideal batch reactor. It therefore assumes steady state and isothermal operation, with complete micromixing. The derivation and the calculated values can be found in the Appendix.
Equation 3- Theoretical Conversion (Lab Manual, 2013)
Equation 3 can be rearranged to give:
Where: k=9.7805L/mol.min at 300C
CA0= CS0*VS0/V0 =0.1mol/L*0.5L/1L =0.05M
The experimental calculations rely on converting the conductivity measurements into the concentration of sodium hydroxide at a given time. This is done via Equation 4. The calculations were performed using excel and the values can be found in the Appendix.
Equation 4- Conversion from Conductivity (Lab Manual, 2013)
Λ = conductivity reading (S)