This experiment aims to determine the relative strengths of hydrochloric acid and urea hydrochloride in hydrolyzing methyl acetate by measuring their rate constants. Methyl acetate will undergo acid-catalyzed hydrolysis, producing acetic acid and methanol. The progress of the reaction is monitored by titrating samples taken at time intervals against standardized sodium hydroxide. Rate constants will be calculated from the titration data and used to compare the strengths of hydrochloric acid and urea hydrochloride in catalyzing the hydrolysis of methyl acetate.

1. SHREE MALLIKARJUN COLLEGE CLASS:FYBSC
SAFETY: Refer to MSDS of methyl acetate, hydrochloric acid, urea hydrochloride, NaOH, phenolphthalein, oxalic acid.
-Dr. Mithil S. FalDesai
Aim: Determination of relative strength between HCl and Urea hydrochloride for hydrolysis of methyl acetate.
.
Chemicals: Methyl acetate, hydrochloric acid, urea hydrochloride, NaOH, phenolphthalein, oxalic acid.
Apparatus/Instrument: Standard volumetric flask, pipette, burette, beakers, conical flask funnel, dropper, glass,
reagent bottle.
Theory: Esters like methyl acetate undergoes acid hydrolysis to produce acetic acid and methyl alcohol.
CH3COOCH3 + H2O → CH3COOH + CH3OH
In the presence of an acid, this reaction should be second-order, as acid and water are reacting molecules are
reacting. But, it is found to be first order. The rate of the reaction is given by
dx/dt = k [CH3COOCH3] [ H2O ] ------- eq 1
Where k is the rate constant. As water is present in a large quantity rate is only dependent on the concentration of
acetic acid. Thus, the rate of reaction is given by
dx/dt = k [CH3COOCH3] ------- eq 2
The progress hydrolysis of methyl acetate is followed by removing a definite volume of the reaction mixture, at
definite intervals of time, cooling it in ice, and titrating the acetic acid formed against standardized sodium
hydroxide. The amount of alkali used is equivalent to the total amount of hydrochloric acid present originally and
the amount of acetic acid formed in the reaction. The relative strength for hydrolysis is measured with respect to
hydrochloric acid and urea hydrochloride.
Procedure:
A) Standardization of ~0.1N NaOH.
The 10 ml of given 0.1N standard oxalic acid is pipetted out into a conical flask and two drops of phenolphthalein
indicator are added. The solution is titrated against the given unknown concentration of NaOH until pale pink colour
is observed. Repeat the titration to get concurrent readings.
B) Standardization of ~0.1N HCl.
The 10 ml of given HCl is pipetted out into a conical flask and two drops of phenolphthalein indicator are added.
The solution is titrated against the given unknown concentration of NaOH until pale pink colour is observed. Repeat
the titration to get concurrent readings.
C) Determination of rate constant in the presence of hydrochloric acid
Take 100 ml of standardized HCl solution in a stoppered reagent bottle and add 5 ml of methyl acetate. Note the
time when half of the methyl acetate solution is transferred in the bottle. Shake the mixture for 10-15 s and pipette
out 5 ml of the reaction mixture in flask containing ice cubes. Titrate the reaction mixture against NaOH solution
using phenolphthalein as an indicator. This burette reading corresponds to ‘Vo’. Repeat the titration at 10, 20, 30,
40, 60 min. Each burette reading corresponds to value corresponds to Vt. The remaining solution is taken in a
stoppered conical flask and heated to 60 ◦C for 15 min. Cool the solution and titrate 5 against NaOH this value
corresponds to ‘V∞’. Repeat the titration to get concurrent readings for V∞. Tabulate the observation in Table 2.
D) Determination of rate constant in presence of urea hydrochloride.
Repeat the above procedure using 0.1 N urea hydrochloride. Tabulate the observation in Table 2.
Plot a graph of log (a-x) v/s time and compare the relative strength between HCl and Urea hydrochloride for
hydrolysis of methyl acetate

2. SHREE MALLIKARJUN COLLEGE CLASS:FYBSC
SAFETY: Refer to MSDS of methyl acetate, hydrochloric acid, urea hydrochloride, NaOH, phenolphthalein, oxalic acid.
-Dr. Mithil S. FalDesai
Observation
Table 1. Hydrolysis of methyl acetate in the presence of HCl
S. No. Time ‘t’
(min)
Burette
reading of
NaOH ‘Vt’
(mL)
V∞- Vt
(mL)
log(V∞- Vt) V∞ - V0
(mL)
𝐾 =
2.303
𝑡
log
𝑉∞ − 𝑉0
𝑉∞ − 𝑉𝑡
1 0
2 10
3 20
4 30
5 40
6 50
7 60
8 ∞ Mean
Table 2. Hydrolysis of methyl acetate in the presence of urea hydrochloride.
S. No. Time ‘t’
(min)
Burette
reading of
NaOH ‘Vt’
(mL)
V∞- Vt
(mL)
log(V∞- Vt) V∞ - V0
(mL)
𝐾 =
2.303
𝑡
log
𝑉∞ − 𝑉0
𝑉∞ − 𝑉𝑡
1 0
2 10
3 20
4 30
5 40
6 50
7 60
8 ∞ Mean
Results: I) Rate constant K =________(Hydrochloric acid)
K =________(Urea hydrochloride)
II) Compare relative strength of hydrolysis with hydrochloric acid and urea hydrochloride.
Questions
1. Why did you observe the difference in rate of the reaction?
2. What is an order of the reaction?
3. What is pseudo first order reaction?
4. What will be the effect of the concentration of reactant on the rate of reaction?
5. Does there is change in concentration of HCl during the hydrolysis?