I’m having trouble answering these questions I’m not sure where I’m going wrong
ID: 554891 • Letter: I
Question
I’m having trouble answering these questions I’m not sure where I’m going wrong please help!
Concentration of NaoH 52 926 Mass of Aspirin Tablet #1 Mass of Aspirin Tablet #2 355 volume of NaOH mixed with Tablet #1 volume of NaOH mixed with tablet #2 Standardization of HCI Trial #1 Mass of Na Co, -083 lume of HCl in burette 50 41.2 Volume of HCl in burette at equivalence point Standardization of HCl Trial #2 091 Initial Volume of HCI in burette 41.2 Volume of HCl in burette at equivalence point 32.4 Mass of Titration of NaOH/Tablet solutions Titration #1-Initial Volume of Hci in burette] 0 mL Titration #1-Final Volume of HCS in burette] 8.801mL Titration #2- Initial Volume of HCI in buretteml Titration #2-Final Volume of HCI in burette 8.30 Concentration of Ha from trial #11.182 IM Inc concentration of HC fron trial #21.195 |M Inc. Average Concentration of HCl Solution .189 M Inc Trial 1- Moles of Acet Trial 1-Masss of Acetyisalicylic acid in tablet Trial 2- Moles of Acetysaine Trial 2 - Mass of Acetylsalicylic acid in tablet acid in t mol Inc acid in tablet Inc % by mass of acetylsalicylic acid in tablet n % by mass of acetylsalicylic acid in tablet #2
Explanation / Answer
Titration,
Standarization of HCl
Trial#1,
moles Na2CO3 = 0.088 g/105.99 g/mol = 0.00083 mol
It reacts with moles of HCl = 2 x 0.00083 mol = 0.00166 mol
Molarity of HCl solution = 0.00166 mol/0.0088 L = 0.187 M
average molarity of HCl = 0.189 M (given above)
3. Analysis of aspirin
mols of NaOH added to the tablet = 0.0926 M x 0.050 L = 0.00463 mol
For T3,
mols HCl used = 0.189 M x 0.0113 L = 0.00214 mol
mols of aspirin present = mols of NaOH consumed
= (0.00463 - 0.00214) = 0.00249 mol
mass aspirin present in the tablet = 0.00249 mol x 180.157 g/mol
= 0.448 g
%aspirin in the tablet = (0.448/0.385) x 100 = 116.36%
The percentage of aspirin by calculations in coming to be greater than 100%. That means we have error in measurement. The error can come from incorrect volume addition of initial NaOH (excess) to the aspirin tablet. Another source of error can come from incorrect standarization of HCl solution used for the analysis of aspirin.
You need to recheck the values to get correct value for the percentage of aspirin in the tablet sample.
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