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

The objective of this experiment is to calculate the % purity of aspirin, by first neutralizing the acetylsalicylic acid with excess sodium hydroxide, and then back titrate the excess

Extracts from this document...

Introduction

The titration of aspirin Objective : The objective of this experiment is to calculate the % purity of aspirin, by first neutralizing the acetylsalicylic acid with excess sodium hydroxide, and then back titrate the excess base with standardised hydrochloric acid. Apparatus : burette, pipette, volumetric flask, funnel. Procedure : 1) About 1.5 gm of aspirin was accurately weighed, the mass was recorded. 2) The weighed amount of aspirin was transferred into a beaker , 25 cm3 of 1 molar NaOH was then transferred into the beaker. The beaker was then gently heated for 10 minutes. 3) After heating, the solution was then transferred into a volumetric flask via a funnel. More distilled water was then added to the flask to make a final volume of 250 a cm3. ...read more.

Middle

7) The above titration is repeated 3 times, and the result is recorded. Result and Calculation: Mass of aspirin = 1.504 gm Concentration of NaOH = 1 mole/L Concentration of HCl = 0.1 mole/L Reaction after adding of NaOH is : 2H2O 1 mole of aspirin will react with 2 moles of NaOH Reaction for the titration is : NaOH + HCl ==> NaCl + H2O 1 mole of NaOH will react with 1 mole of HCl The result of the titration is tabulated as follows: Burret Reading Titration 1 Titration2 Titration Final Reading 9.2 16 25 Initioal reading 0 7.0 16 Volume used 9.2 9 9 % purity 94.55% 95.74% 95.74% Calculation : Sample calculation using result of titration 2 # moles of HCl use = Molarity * Volume in litres ...read more.

Conclusion

Of the above only 0.09 moles was left behind, so the aspirin has reacted with 0.025 - 0.009 = 0.016 moles of NaOH. 1 mole of aspirin will react with 2 moles of NaOH So the number of moles of aspirin must be 0.016/2 = 0.008 moles Molecular mass of aspirin (C9H8O4) = 180, so mass of acetylsalicylic acid = 0.008 * 180 = 1.44 g So % purity of aspirin = (1.44/1.504) * 100 = 95.74% The other titration results was calculated the same way. Average purity = 1/3 (94.55 + 95.74 + 95.74) = 95.34% Conclusion and discussion: The error in this lab is in the judgement of the end-point, in which the solution will completely becomes colourless. The result was quite consistent, the average % purity is 95.34% ...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. Determining the purity of Iron Wool.

    Using a funnel 0.02 mol dm-3 potassium manganate VII solution was poured into a burette up to 0.00cm3 mark and titrated until a permanent overall pink-ish colour change occurred. This reading was noted and the titration portion of the experiment was carried out two more times with all readings noted and the average of them used in the final calculations.

  1. Titrating Sodium hydroxide with an unknown molarity, against hydrochloric acid to find its' molarity.

    Accuracy and precision of equipment used: * 25cm� (grade B) graduated pipette: this reads correct to the nearest 0.5cm� * Top pan balance: this reads to the nearest 0.01g * 50cm3 (grade B) burette: this reads correct to the nearest 0.5cm3 Method To ensure that all equipment is clean, first

  2. Preparation of aspirin - The chemical background This is the overall reaction that ...

    Although it is not an equilibrium reaction. Method Step 1: The preparation of 2-hydroxybenzoic acid in a hydrolysis reaction: Reflux apparatus Stage 1- safety glasses must be worn . Set up quick fit apparatus and a water bath using 200 cm3 beaker.

  1. Investigating different types of aspirin and making aspirin.

    When identifying the components some of them will be coloured and so will be visible but often they will not be visible. So then there are a lot of techniques that's can used to see them: * Specially pre-treated plates when exposed to ultraviolet light reveal substances as pale purple spots.

  2. 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.

  1. Investigation in to discover the percentage of acetylsalicylic acid in a sample of aspirin ...

    Despite its usefulness, there is a danger to taking too many aspirin. Over time aspirin can cause gastronomical bleeding that leads to iron deficiency, and also gastric ulcers may occur. They should not be given to children as it increases the risk of contracting Reye's syndrome, a serious and often fatal disease of the brain and some abdominal organs.

  2. the synthesis of azo dyes, aspirin and soap

    The reaction takes place under 10�C to prevent the NN, the N2 diazonium ion decomposing into N2 gas. This suggests that the delocalization of the diazonium ion bond electrons over the benzene ring is only able to stabilize the diazonium salt at cold temperatures.

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