Lab report – Aspirin 2.0
John Kastl
Objective:
To make acetylsalicylic acid (aspirin) crystals from salicylate, then titrate with NaOH
to calculate the mass percent of aspirin in the crystals.
Reactions:
C7H6O3 + C4H6O3  C9H8O4 + HC2H3O2
Redissolve, cool solution  aspirin crystals + solution with impurities
NaOH + KHP  NaHP + KOH
NaOH + C9H8O4  H2O + NaC9H7O4
Calculations:
Theoretical yield:
1. 2.47g Salicylic acid (1 mol S.A / 138g S.A.)(1 mol aspirin / 1 mol S.A.)(180g
aspirin / 1 mol aspirin) = 3.22g
2. (5.00mL)(1.69g/mL) (1 mol S.A / 102g S.A.)(1 mol aspirin / 1 mol
S.A.)(180g aspirin / 1 mol aspirin) = 14.9g
3. Salicylic acid is the limiting reagent, so the percent yield is 3.22g
Percent yield:
1. Only 2.47g aspirin was produced, so now percent yield is calculated
2. 2.47g / 3.22 = 76.7%
Molarity of NaOH for standardization titration
1. .81g KHP (KC8H5O4) (1 mol KHP / 204g KHP) (1 mol KHP / 1 mol NaOH)(1 /
.03875 L) = .102 M
2. .77g KHP (1 mol KHP / 204g KHP) (1 mol KHP / 1 mol NaOH)(1 / .03875 L)
= .105 M
3. .89g KHP (1 mol KHP / 204g KHP) (1 mol KHP / 1 mol NaOH)(1 / .03875 L)
= .106 M
Mass percent of aspirin in each sample:
1. (.105 M
Aspirin)
2. (.105 M
Aspirin)
3. (.105 M
Aspirin)
NaOH)(.02145 L)(1 mol Aspirin / 1 mol NaOH)(180g Aspirin / 1 mol
= .405g Aspirin, so .356g / .405g * 100 = 87.9%
NaOH)(.01759 L)(1 mol Aspirin / 1 mol NaOH)(180g Aspirin / 1 mol
= .322g Aspirin, so .305g / .332g * 100 = 91.8%
NaOH)(.01801 L)(1 mol Aspirin / 1 mol NaOH)(180g Aspirin / 1 mol
= .340g Aspirin, so .305g / .340g * 100 = 89.7%
Mass percent of Aspirin in commercial tablet:
1. (.105 M NaOH)(.01361 L)(1 mol Aspirin / 1 mol NaOH)(180g Aspirin / 1 mol
Aspirin) =.257g Aspirin, so .257g / .280g * 100 = 91.8%
Spectrophotometric analysis:
This was done to confirm the results of the percent yield of aspirin, data not
available at time of submission.
Discussion:
Acetaminophen
Functional groups: alcohol, amide, aromatic ring, ketone
Naprosyn
Functional groups: Carboxylic acid, two aromatic rings, ether
Dextropropoxyphene
Functional groups: ether, amide, two aromatic rings
Source: Wikipedia