IA on aspirin hydrolysis in different medium, water vs acid (1M) medium, measured using visible spectrophotometer.

1. Aspirin hydrolysis
Aspirin undergo hydrolysis to produce salicylic acid (SA) and acetic acid.
SA, active ingredient will react with Fe3+ to form violet product.
Standard calibration plot was done using SA.
Conc range from (1.56, 3.125, 6.25, 12.5, 25.0) in mg/100
1% FeCI3 solution was prepared.
Violet colorization monitored with colorimeter.
Fe3+ reacts with SA to produce
violet substance which can be measure with colorimeter
Procedure:
Standard calibration plot done using SA ranging from (1.56 – 25.0)mg/100
0.025g SA dissolve in 100ml water. (25mg/100). Half fold serial dilution was done.
1ml SA of diff conc added to cuvette.
100ul of Fe3+ added and mix.
Abs was done at 565nm
Mechanism of aspirin hydrolysis to produce SA Aspirin 500mg was turn
into powder
Aspirin hydrolysis in diff medium, water vs acid (1M) medium, measured using visible spectrophotometer.

2. Go to expt – press calibrate Insert cuvette (violet sol), press collect
Insert a blank containing water
Press stop, and click on rainbow icon. Select abs vs conc. λ max at 565nm will
be automatically chosen
Type in concentration and press keep
Type in concentration and press keep
for 5 diff conc
Standard calibration plot is generated
Aspirin hydrolysis in diff medium, water vs acid (1M) medium, measured using visible spectrophotometer.

3. Hydrolysis of aspirin is very slow in acid (1M) medium compared to water
0
2
4
6
8
10
12
HCI water
Mass
of
salicyclic
acid/mg/100ml
Water vs HCI
Aspirin hydrolysis in diff medium water
and acid
y = 0.0945x + 0.016
R² = 0.9999
0
0.5
1
1.5
0 2 4 6 8 10 12 14
Abs
conc/mg/100
conc vs abs
Line best fit Abs = 0.0945 (Conc) + 0.016
500mg aspirin dissolved in 100ml water/ethanol mix.
Expected conc – 382mg/100ml.
Abs from aspirin found to be 0.938
Abs = 0.0945 (Conc) + 0.016
0.938 = 0.0945 (Conc) + 0.016
Conc = 9.75mg/100
1mol aspirin produces - 1mol SA
500mg aspirin contain 0.00277mol
0.00277mol aspirin produces 0.00277mol SA
RMM SA – 138.
0.00277mol x 138 = 382mg SA
500mg aspirin dissolved in 100ml water/HCI (1M) /ethanol mix.
Expected conc – 382mg/100ml.
Abs from aspirin found to be 0.744
Abs = 0.0945 (Conc) + 0.016
0.744 = 0.0945 (Conc) + 0.016
Conc = 7.70mg/100
Aspirin hydrolysis in diff medium, water vs acid (1M) medium, measured using visible spectrophotometer.