• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Determine the percent aspirin in an aspirin tablet and to compare this with the amount specified on the label.

Extracts from this document...

Introduction

Titrimetric Analysis of Aspirin Name: Andrew Holmes Student Number: 2103086 Course: BSc Forensic Science Year: 1 Unit: Introduction to Forensic Chemistry Date: 18/03/02 Summary The purpose of the experiment was to determine the percentage of acetyl salicylic acid in an aspirin tablet and to compare this with the amount specified on the label. The average weight of one tablet before titration was found to be 328 mg. The amount of aspirin calculated from the results obtained from titrimetric analysis to be 317 mg. The stated dose of the tablets was 300 mg The percent purity of an aspirin tablet to the amount specified on the label was then calculated to be 96.47 % pure. Aims and Objectives Objectives The objectives of this experiment are to determine the percent aspirin in an aspirin tablet and to compare this with the amount specified on the label. This is carried out using an acid - base titration. Aims The aims of the experiment were as follows: * Calculate the weight of one aspirin tablet. * Calculate the molarity of diluted and stock NaOH solutions. * Calculate the no. Of moles used in hydrolysis. * To determine the percent aspirin in an aspirin tablet and compare it with the amount specified on the label. ...read more.

Middle

25 cm3 of the hydrolysed solution is pipetted into a clean conical flask. 15 drops of phenolphthalein was added to act as an indicator. The solution was then titrated with standard 0.1 mol dm-3 hydrochloric acid. The hydrochloric acid is then released from the burette slowly ensuring the hydrolysed solution is mixed constantly. The starting point of the hydrochloric acid in the burette must be recorded before the titration can begin. The end point is reached when the pink colouring of the indicator is reduced so it is a clear liquid. The titrations are repeated until the titration data is reproducible. The apparatus must be cleaned and dried after each titration to ensure accurate results are achieved. Serval safty precautions must also be practiced. A lab coat must be worn at all times during the lab and long hair tied back. Also safety goggles must be worn when heating the acetyl salicylic acid and the sodium hydroxide. Results 1. Standardisation of 25cm3 sodium hydroxide solution. Burette Readings Initial Reading (cm3) Final Reading (cm3) Volume Used (cm3) Titration 1 1.30 27.40 26.10 Titration 2 1.60 26.00 24.40 Titration 3 0.70 25.15 24.45 Average volume of 0.1 mol dm-3 hydrochloric acid used = 24.98 2 d.p 2. Label information for the aspirin. ...read more.

Conclusion

* The number of moles of sodium hydroxide used in hydrolysis can be calculated by subtracting the number of moles of sodium hydroxide taken for hydrolysis by the number of moles of sodium hydroxide remaining after hydrolysis. * The weight of one aspirin tablet was calculated by working out the molecular weight of aspirin and multiplying it by the number of moles of aspirin used, to find the weight of the sample of aspirin used in the experiment; and then dividing it by the number of tablets in the sample. * In an acid-base titration, as a strong acid is gradually added to a strong base, it reacts with the base and the pH gradually falls. * Accuracy and precision of the measurements taken in the experiment can influence the data obtained. Experimental error in the results may have been due to the use of inaccurate glassware, human error, systematic error in the * Measurements that will influence the calculations made from the data obtained, glassware not properly rinsed and dried before use, dirt and air on the analytical balance, or the acetyl salicylic acid not fully hydrolysed. * The correct safety precautions were adhered to during experimentation. These included handling glassware in a careful and appropriate manner, wearing safety goggles during the heating stage of the experiment, and using tongs and a heatproof mat. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Aqueous Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Aqueous Chemistry essays

  1. Marked by a teacher

    ANALYSIS OF ASPIRIN BY BACK TITRATION

    4 star(s)

    The name derives from the Latin word for the willow tree (Salix), from whose bark it can be obtained. SAFETY Hand glassware in an appropriate manner. Wearing safety goggles and lab coats during the heating stage of the experiment Use tongs to handle hot flasks METHOD Apparatus used Conical flask

  2. Indigestion Tablets Investigation

    I believe this difference comes from two reasons, firstly because there was a very brief time lapse between dropping the tablet into the acid and replacing the bung and secondly because the very hot acid would have produced CO2 of a higher temperature.

  1. Investigation into the efficiency of various indigestion tablets.

    = 0.022882 x 4.936 = 0.1129455 (times more) = 112.9 mg NaHCO3 Mass found in one tablet (mg) Setlers (1.22675g) Rennie (1.315g) Bisodol (1.234g) CaCO3 556.9 663.8 547.5 MgCO3 Not present 65.4 59.9 NaHCO3 Not present Not present 112.9 Total 454.0 553.7 601.3 Mass found in 1g of tablet (mg)

  2. A titration to determine the ratio of moles of Sulfamic acid to Sodium Hydroxide ...

    Part 2:filing burette >Make sure nozzle is closed and burette is clamped securely. >Fill with NaOH to above the 0 point but below the top with a beaker and funnel. >Remember to hold the funnel above the rim and to remove it afterwards.

  1. Making Aspirin.

    Unfortunately, Hoffmann had to wait for fame. He finished his initial studies in 1897, and his employers didn't pay much attention to it because it was new and they were cautious - they didn't think it had been tested enough.

  2. To employ iodometric titration to determine the content of vitamin C in commercial tablets ...

    A portion of the prepared potassium iodate(V) solution was poured from the volumetric flask to a clean and dry 100 cm3 beaker. 5. A 25.00 cm3 pipette was rinsed with distilled water, and then with the potassium iodate(V) solution.

  1. Analysis of the content in Aspirin Tablet

    As the number of moles of sodium hydroxide used in hydrolysis is known, the number of moles of sodium hydroxide used to react with aspirin can be calculated by subtracting the original number of moles of sodium hydroxide from the number of moles of the excess sodium hydroxide.

  2. Determination of the vitamin C content (ascorbic acid) of a commercial vitamin Ctablet and ...

    of the standard potassium iodate solution into the conical flask using a pipette and a pipette filler. 14. The initial burette reading is recorded in table 2. The resulting solution containing excess iodine is immediately back titrated with the standard sodium thiosulphate solution.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work