Physical Principles II
CEBU CITY
Chemical Engineering Department
Name: Juphil Lamanilao Date: October 15, 2009
Course & Yr: BSChE-4
I.TITLE: Equilibrium in Organic Liquids
II.OBJECTIVE:
• To determine the equilibrium constant of each mixture.
III.APPARATUS:
Base burette, 5-ml pipette, 1-ml pipette, 7 test tubes with cork, 0.5N NaOH,
phenolphthalein, CH3COOC2H5, conc. HCl, glacial CH3COOH, absolute C2H5OH
IV.SKETCH:
Equilibrium in Organic Liquids 1

Physical Principles II
V.TABULATED DATA & RESULTS:
Wt. of Wt. of tube Wt. of Volume of
Test tube Components empty with Solution NaOH Kc
tube solution used
5ml 3N HCl
1 + 5ml H2O 17.24 27.61 10.37 43.1 7.77x10-3
5ml 3N HCl+
2 5ml EtOAc 17.51 27.15 9.64 101.5 0.0192
5ml 3N HCl
3 + 5ml EtOAc 17.51 27.39 9.86 113 6.81x10-4
5ml 3N HCl
4 + 2ml EtOAc 20.01 29.95 9.97 82.6 4.78x10-4
+ 1ml EtOH
5ml 3N HCl
5 + 4ml EtOAc 17.47 27.09 9.62 97.9 5.48x10-3
+ 1ml EtOH
5ml 3N HCl
6 + 4ml EtOAc 17.31 27.20 9.89 142.9 9.96x10-4
+ 1ml glacial
5ml 3N HCl
7 + 4ml EtOH+ 17.65 25.09 7.44 44.1 7.91x10-3
1ml glacial
VI.SAMPLE COMPUTATIONS:
@ 25оC
HCl = 1.7899 g/ml CNaOH= (0.5M)(100ml)/ 43.1 ml = 1.16 M
CH3COOH = 1.0498 g/ml CH2O= 4.48g÷18g/mol x 51000L = 49.78 M
EtOAc = 0.897 g/ml CHCl= 3M
mHCl= 1.1789 g/ml (5ml) = 5.89 g Kc= CNaOH/ (CHCl x CH2O) = 7.77x10-3/M
mH2O= (10.39- 5.89) = 4.48 g
VII.DATA ANALYSIS:
From the exact molarity of both the 3 M HCl and the 0.5 NaOH and the titration
volume, the equilibrium amounts of the four substances in the equilibrium mixture can
be determined, and the equilibrium constant evaluated. Experimental values gathered
for the equilibrium constant in each organic liquids are comparably far since each
Equilibrium in Organic Liquids 2

Physical Principles II
mixture has varying components. Furthermore, organic compounds are covalently
bonded which indicates that their rates of reaction are quite slow. It is much slower
than the usual hydrolysis and esterification processes. Each mixture contain little
amount of HCl to aid the reaction. HCl and ethyl acetate has the highest K c while HCl,
ethyl acetate and water has the smallest Kc value. The larger the Kc value, the more
spontaneous the reaction may become. So, HCl and ethyl acetate gives the most sponta-
neous reaction since its Kc value is the largest while HCl, ethyl acetate and water yields
the opposite value.
VIII.APPLICATION TO ChE:
Knowledge of equilibrium constant for a given reaction is very helpful aid in
laboratory analysis as well as in industry. From a practical standpoint, if you are in a
business of producing a given chemical product, it would be essential to know the "K"
of a reaction so that you could optimize the yield of the product. Whereas, in laboratory
analysis, it is used to predict the direction of the reaction and the extent to which a
reaction occurs.
IX.CONCLUSION:
The equilibrium system is ethanol-acetic acid-ethyl acetate-water. The equation
for this equilibrium is:
C2H5OH + CH3COOH <-----> CH3COOC2H5 + H2O
Equilibrium is established very slowly at room temperature when these four sub-
stances are mixed. The rate of reactions (both forward and reverse) can be accelerated
by using a catalyst so that the equilibrium can be more rapidly established. 3N HCl is
used in this experiment as a catalyst. The mixtures are allowed to stand at room temper-
ature, then aliquots of each mixture are titrated with a standard NaOH solution. The
amount of HCl in these mixtures is unchanged since the HCl is only a catalyst. The
amount of NaOH required in each titration is equivalent to the amount of HCl and the
acetic acid acid in the equilibrium mixture. The amount of acetic acid at equilibrium can
be calculated easily from the amount of NaOH used in the titration. The amount of
acetic acid found is used to calcuate the amounts of the remaining three substances. The
equilibrium constant is then calculated by the equation:
Kc = [ethyl acetate] [water] / [ethanol] [acetic acid]
The four quantities in the above equation may be replaced by the number of
moles of the four substances involved since the volume is constant in each mixture.
Equilibrium in Organic Liquids 3