Part of The Student Room Group

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

Experiment: Analysing molar mass of Aspirin

Extracts from this document...

Introduction

Experiment: Analyzing molar mass of aspirin Introduction In 1899 the Bayer Company of Germany introduced the ethanoate ester of salicylic acid naming it, ?Aspirin?. Aspirin is an acid, it can be titrated with a base such as sodium hydroxide to the equivalence point. The following chemical equation describe the acid-base reaction that will be observed in this experiment. H-Aspirin + NaOH ------> Na-Aspirin + H2O (acid) (base) (salt) The above chemical equation is balanced as written. An indicator will be used to provide a way to visually determine the endpoint of the titration. Phenolphthalein changes from colourless to a faint pink while bromothymol blue changes from yellow to a faint blue at a pH of around 8. Aim To calculate the molar mass of Aspirin Hypothesis The chemical formula of Aspirin is C9H8O4. It can also be written as C6H5(OCOCH3)COOH. In this experiment, Aspirin, which is an acid, will react with sodium hydroxide, NaOH in an acid-base reaction to produce salt and water. This analysis makes use the fact that aspirin is a monoprotic acid and therefore reacts with NaOH according to the equation: C6H5(OCOCH3)COOH + NaOH ------> C6H5(OCOCH3)COO+Na- + H2O (acid) ...read more.

Middle

Repeat the experiment, but instead of phenolphthalein, use bromothymol blue as indicator. It is not necessary to clean out your burette of NaOH before you start the second experiment. Simply refill your burette and then start again. Data Collection and Processing Raw data Burette reading (± 0.05) ml Experiment A (with Phenolphthalein) Experiment B (with Bromothymol blue) 1st 2nd 3rd 1st 2nd 3rd Initial reading 0.0 16.0 31.9 0.0 15.1 30.9 Final reading 16.0 31.9 48.4 15.1 30.9 46.5 Volume used 16.0 15.9 16.5 15.1 15.8 15.6 Experiment Observation Initial pH Final pH A (Phenolphthalein) Color change from colorless to faint pink 4.3 8.7 B(Bromothymol blue) Color change from yellow to faint blue 4.2 8.6 Calculation 1. Experiment A C6H5(OCOCH3)COOH + NaOH ------> C6H5(OCOCH3)COO+Na- + H2O Average volume of NaOH used= = 16.1 ml No. of mol of NaOH= = 0.00161 mol Criterion C6H5(OCOCH3)COOH NaOH Equation mol 1 1 Real mol x 0.00161 mol No. of mol of C6H5(OCOCH3)COOH, x = 0.00161*1 = 0.00161 mol Mass of one tablet of aspirin, C6H5(OCOCH3)COOH= 300 mg or 0.3 g Molar mass of C6H5(OCOCH3)COOH = = = 186.33541 gmol-1 Percentage error= = 3.429% 1. ...read more.

Conclusion

This is the reason why phenolphthalein indicator is able to produce more accurate result than bromothymol blue. Evaluation There are some weaknesses that were detected throughout the experiment. Firstly, the volume of indicator are not fix in this experiment. Using drops is not really suitable as it may distort the volume of indicator in this experiment. The difference may not really big but it still can affect the final result. Secondly, the mixture of aspirin, C6H5(OCOCH3)COOH and sodium hydroxide, NaOH is not stirred during the titration. This may produce uneven and not uniform result as the NaOH is not totally mix with the aspirin. The neutralization process may only occur on the surface of the aspirin solution. Having said that, this experiment is successfully analyzing the molar mass of aspirin. The experimental value is close to the theoretical value. Further improvement In order to improve the results of the future experiments, several ways can be implemented. Firstly, the volume of indicator use should be fixed instead of using drops. By using this way, the level of uncertainty of the final results can be reduced. Besides that, the mixture of aspirin solution and NaOH need to be stirred throughout the titration process. More uniform results can be obtained by implementing this method. ...read more.

The above preview is unformatted text

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

Found what you're looking for?

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

or


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 International Baccalaureate Chemistry essays

  1. The purpose of this experiment was to determine the molar mass of carbon dioxide ...

    = 41.9 g mol-1 Extra questions: 1) What value does the experiment give for the relative molecular mass of CO2? The relative molecular mass of CO2 was 41.9. 2) Calculate the density of CO2 at s.t.p from your results.

  2. Preparation of Aspirin Lab

    x 100 = 43.7816 +/- 0.0002 % Uncertainty: 0.0002/ 0.5806 = 0.0003445 0.000001/1.326127 = 0.0000007541 0.0003445 + 0.0000007541 = 0.000345 0.000345/ 100 x 43.78 = 0.0002 Questions: 1. Relative Molecular Mass of Salicylic Acid: 7 (12.011) + 3 (15.999) + 6 (1.0079)

  1. Can one determine the coefficients of a balanced chemical equation by having the mass ...

    14. Take a funnel large enough to just fit in a 150mL beaker, the second 150mL beaker and a filter paper small enough to just fit in this funnel. Determine the mass of the filter paper so that the mass of the copper can later be isolated in the calculations.

  2. Molar Heat combustion chemistry - investigate the effect of molar mass on the molar ...

    of combustion of adjacent members of a homologous alcohol series, with the first 5 being the adjacent members. Methanol, ethanol, 1-propanol, 1-butanol and 1-pentanol, which follows the rule CnHn+1OH, where n > 1. It is evident from graphs 1 and 2 that as the molar mass increases, the molar heat of combustion increases.

  1. titration experiment

    With around or slightly over 30?, the color of NaOH turned to be very likely to transparent. We found out that a drop would change the color of the solution. The average concentration of the NaOH solution is 0.0987 �1.36% M *note: for the experiment part 1, we used metallic

  2. IB questions and answers on Atomic Theory

    How do scientists use bright line spectra to identify unknown elements in far off stars or other samples of matter? Known samples of elements are studied and the bright line spectrum is recorded. These known spectra can be compared to the unknown spectra seen when looking at the light from a far away star through a spectroscope.

  1. Experimental Molar Enthalpy of Neutralization for Sodium Hydroxide Solution

    The theoretical (actual) value given is obtained at SATP conditions; however, when the following lab was conducted, the conditions were not at SATP. SATP conditions are at 100kPa and 25ËC. The conditions when the lab was conducted were at 101.9kPa and 25ËC.

  2. Chemistry Titration Acid Base Lab

    This is because it would have provided one with the knowledge of the types of errors that occurred and how much it affected their data. For instance, Sarah and I compared our results with Rachel Hung and Yashna Lakhani?s group.

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