NAME: HIEP TON
February 22, 2015
Exp 8 ASPIRIN SYSTHESIS
I.
INTRODUCTION:
The purpose of this lab is to find the purity of the synthesized aspirin or
a commercial aspirin tablet. Aspirin has been using as pain-killer
(analgesic) and fever-reducing drug (antipyretic). Acetylsalicylic acid
remains intact in the acidic stomach. Aspirin’s molar mass is 180.2
g/mol. Salicylic acid’s molar mass is 138.1 g/mol. Acetic anhydride’s
molar mas is 102.1 g/mol. Aspirin is a weak monoprotic acid. From the
melting point, the purity of an aspirin can be determined. Melting point
is essentially independent of atmospheric pressure. The degree of
lowering the melting point depends on the nature and the concentration
of the impurities. Purity can be determined by acid-base titration.
mole acetylsalicylic acid ×
% 𝑝𝑢𝑟𝑖𝑡𝑦 =
II.
180.2 g
= gram acetysalicylic acidic
mole
gram acetysalicylic acidc
× 100
gram aspirin sample
PROCEDURE:
In the first lab day, Aspirin was prepared in the fume hood. In 125mL
Erlenmeyer flask, two grams of salicylic acid was measured. 4-5mL
acetic anhydride and salicylic acid were swirled. After adding 5 drops of
H2SO4, the Erlenmeyer flash was put in a 400mL boiling water bath
beaker. After 15 minutes, the flash was removed. The flask was added
10mL of deionized ice water, swirled, and placed in the ice bath until no
crystal form. The filter paper was sealed in Buchner funnel by 0.5mL of
water. The mixture in the flash was decanted onto the filter paper. The
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NAME: HIEP TON
February 22, 2015
amounts of added water were recorded each time added. The solid on the
filter was kept for the second lab day. In the second lab day, After the
solid was dry out, the crystal was transferred to a 100mL beaker. 20mL
of ethanol was added to dissolve the crystal. The water was kept adding
into the beaker, which was placed on the 60oC hotplate, until the mixture
got absolute cloudy. The beaker was placed in the ice bath until the
crystal of acetylsalicylic acid from. The filter paper was sealed in
Buchner funnel by 0.5mL of water. The mixture in the flash was
decanted onto the filter paper. The amounts of added water were
recorded each time added. The solid on the filter was kept for the third
lab day. In the third lab day, After the solid was dry out, the crystal was
put in the one-open-end capillary tube for 1cm depth. The capillary was
placed in the mel-temp apparatus. The temperature of the solid when
started to melt and when was totally melted were recorded. Mel-temp
apparatus was returned to the stockroom and chemical was disposed
according to the instruction from the instructor.
III.
DATA & RESULT:
Sample mass
Volume of added ethanol
Volume of added acetic anhydride
Crystal mass
Time of water
added
1st
2.0037
gram
9.500 mL
4.300 mL
0.9980
gram
Volume of water added
(mL)
10
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NAME: HIEP TON
February 22, 2015
2nd
3rd
4th
5th
6th
7th
Total
Temperaturewet
Temperaturesolid-
15
30
10
10
10
15
100
Trial 1
122.0oC
129.3oC
Trial 2
127.0oC
132.7oC
Trial 3
119.8oC
132.3oC
gone
IV.
RESULT & DISCUSSION:
The percent purity of aspirin as calculated below was 47.73%. The
possible error that made the percent purity was not close to 100% might
be the amount of water added during the filtering times. The amount of
water might be added not enough.
V.
CONCLUSION:
Through filtering the salicylic acid, acetic anhydride mixture and
gaining the mass of the aspirin crystal, the purity of the aspirin was
determined.
VI.
CACULATION:
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NAME: HIEP TON
February 22, 2015
Actual Value:
gram salicylic acid sample ×
2.0037g ×
1 mol
= mole salicylic acid sample
138.1g
1 mole
= 0.01451 mol salicylic acid sample
138.1g
mol salicylic acid sample ×
0.01451 mol ×
180.2 g
= gram acetysalicylic acidic
mole
180.2 g
= 2.615 g acetysalicylic acidic
mol
𝐏𝐮𝐫𝐢𝐭𝐲 𝐰𝐢𝐭𝐡𝐨𝐮𝐭 𝐚𝐝𝐝𝐞𝐝 𝐰𝐚𝐭𝐞𝐫
Experimental Value: 0.9980 gram
Purity:
% 𝑝𝑢𝑟𝑖𝑡𝑦 =
Experimental Value
× 100
Actual Value
% 𝑝𝑢𝑟𝑖𝑡𝑦 =
0.9980 g
× 100 = 38.17 %
2.615 g
𝐏𝐮𝐫𝐢𝐭𝐲 𝐰𝐢𝐭𝐡 𝐚𝐝𝐝𝐞𝐝 𝐰𝐚𝐭𝐞𝐫
Experimental Value:
𝐴𝑑𝑑𝑒𝑑 𝑤𝑎𝑡𝑒𝑟 1
100 1
(
× ) + 𝐶𝑟𝑦𝑠𝑡𝑎𝑙 𝑀𝑎𝑠𝑠 = (
× ) + 0.9980 = 1.248
100
4
100 4
Purity:
% 𝑝𝑢𝑟𝑖𝑡𝑦 =
Experimental Value
× 100
Actual Value
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NAME: HIEP TON
% 𝑝𝑢𝑟𝑖𝑡𝑦 =
February 22, 2015
1.248 g
× 100 = 47.73 %
2.615 g
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