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phrm235aspirin

# phrm235aspirin - Graham Barnett Jillian Daviau Nick Baccari...

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Graham Barnett Jillian Daviau Nick Baccari PURPOSE: The purpose of this experiment was: To determine the amount of aspirin in each tablet of aspirin To carry out procedures and calculations using acid/base titration studies To understand how hydrolysis plays a part in the shelf life of drugs that contain aspirin. EXPERIMENTAL DATA: Newest 2003 New 1999 Old Water/Blank 1) Mass of whole aspirin (grams) 0.366 0.349 0.380 N/A 2) Mass of crushed aspirin (grams) 0.361 0.349 0.354 N/A 3) % recovery = (crushed/whole)*100 98.6 99.8 93.1 N/A 4) Amount of NaOH added to titrate (ml) 20.2 21.5 20.0 Average=20.5 (H 2 O was substituted for NaOH in blank) 5) Amount of extra NaOH added = (Row4 +10ml) 30.2 31.5 30.0 30.5 6) Amount of HCl to back titrate (ml) 7.7 8.8 7.5 23.8 7) Amount NaOH –HCl 22.5 22.7 22.5 6.7 * 8) =(Row5)(0.22 ** ) 6.64 6.93 6.6 ** 9)ml NaOH= (Row7)-(Row8) 15.9 15.8 15.9 N/A 10) moles NaOH 0.00159 0.00158 0.00159 N/A 11) grams ASA = (moles NaOH)x(180g) 0.286 0.284 0.286 N/A 12) ASA (mg)= 1000 x (grams of ASA) 286 284 286 N/A 13) Assumed amount of ASA in crushed tablet (mg) = (% recovery)x(***) 320 324 303 N/A 14) Amount of ASA lost from original (mg) = (row13)-(row12) 34 40 17 N/A * CO 2 + H 2 O -------- H 2 CO 3

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NaOH ------ Na 2 CO 3 + H 2 O The blank represents the amount of NaOH consumed by CO 2 from the atmosphere, this value was 6.7 ml. ** Since 30.5 ml of NaOH was added to the blank, the percent of NaOH absorbed by CO 2 was found by: 6.7/30.5=0.22 ***Amount of aspirin contained in one tablet according to bottle label: 325mg
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