Aspirin Essay

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Title: Analysis of Aspirin by Back Titration Name: ------------------------------------------------- Date: 11/11/12 Co-Worker: Abstract The amount of aspirin in an aspirin tablet was determined. The method of back titration was used. The amount of aspirin in each tablet was determined to be 450mg. the percent of aspirin in an aspirin was found to be 92.78%. The results gotten did not meet the QC Acceptance criteria for %Recovery or %RSD. Introduction Aspirin was analysis by back titration. A back titration is where the concentration of an analyte is determined by reacting it with a known amount of excess reagent. The remaining excess reagent is then titrated with a second reagent. The results from the second titration show how much of the excess reagent was used in the first titration and the original analyte's concentration is then determined. C9H8O4+2NaOH → C2H3O2Na+ H2O+Excess NaOH H2SO4+2NaOH → Na2SO4+2H2O Results | 1 | 2 | 3 | 4 | Start Point | 0.0cm³ | 0.0cm³ | 0.0cm³ | 0.0cm³ | End Point | 10.6cm³ | 10.0cm³ | 10.0cm³ | 10.0cm³ | Titre | 10.6cm³ | 10.0cm³ | 10.0cm³ | 10.0cm³ | Table 1: Shows results from the standardisation Titration. | 1 | 2 | 3 | 4 | Start Point | 0.0cm³ | 15.0cm³ | 30.0cm³ | 0.0cm³ | End Point | 14.8cm³ | 30.0cm³ | 45.0cm³ | 15.0cm³ | Titre | 14.8cm³ | 15.0cm³ | 15.0cm³ | 15.0cm³ | Table 2: Shows the results from the back Titration. Weight of weighing boat: 2.091g Weight of weighing boat + aspirin: 2.577g Weight of aspirin: 0.485g Calculations molesNaOH =molesNaOH reacted with aspirin+ molesNaOH reacted with H2SO4 Molar Ratio: NaOH: Aspirin – 2:1 NaOH: H2SO4 – 2:1 Standardisation | Burette | Conical Flask | | H2SO4 | NaOH | Concentration | 0.05 M | X M | Volume | 10 cm³ | 10 cm³ | n | 1 | 2 | m x vn= m1 x v1n1 0.05M × 10cm³1=10cm3xM2 0.5M/cm³=10cm3xM 2

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