- Unit Operations
Kinetics Saponification Experiment
– Unit Opertaions Biotechnology Room EB256
– Ethyl Acetate, Sodium
Hydroxide, Sodium Acetate
determine equation(s) that demonstrate the kinetics of a known reaction.
Possible objectives may include the derivation of a rate law, its
reaction order and rate constants, the activation energy, and equilibrium
rate laws can be derived either by the differential method, the integral
method, the method of initial rates, the method of excess, and/or the method of
half-lives as demonstrated in Fogler, Ch. 5.
The Arrhenius Law is needed to determine the activation energy as shown
in Fogler, Ch. 3.
stirred tank is located in Room 256 of the Engineering Building. It contains a
heat jacket, which is connected via tubing to a water bath, to provide a
constant temperature. It also contains a stirring impeller and a rotary magnet
to assist in mixing.
to the reactor is a pH meter, which is interfaced with an IBM-compatable
computer via an RS-232 cable. Before use every day, the pH-meter needs to be
calibrated using two different pH-standard buffers. Select two from among this list: pH= 4, 7, or 10.
BE CAREFUL WITH THE pH ELECTRODE! You
must be certain to return the pH electrode to its standard solution when not in
use. The computer software will allow pH and temperature readings
to be taken and stored as a function of time using a time interval selected by
the user. The data can be easily transferred/converted into a spreadsheet.
Detailed instructions are given below.
The reaction to
be investigated here is known as a saponification reaction:
Acetate + Sodium Hydroxide <-----> Ethanol + Sodium Acetate
Some notes about this reaction:
reaction by combining aqueous NAOH solution and aqueous ethyl acetate solution,
not by adding pure ethyl acetate to the NaOH solution.
After the pH
meter is calibrated and the computer "booted up", data acquisition
can begin. Follow these instructions:
At this point, the data: time, pH and temperature, will transfer to the screen, as can be observed.
"Setup" key twice (to arrive at Menu #2)
electrode is very fragile. Be careful! Never use the pH electrode
as a stirring rod. Also take care in placing the electrode inside of the
reactor. Make sure that the impeller does not harm the electrode. If you
suspect that the electrode is not functioning properly, see the TA or lab
Fogler, H.S., Elements of
Chemical Reaction Engineering, 2nd ed., Prentice-Hall, 1992.