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

To Estimate the Purity of Commercial Nitrite

Extracts from this document...

Introduction

Date: 9/9/10 Experiment No.: 1 Title: To Estimate the Purity of Commercial Nitrite Object: The purpose of this experiment is to check the purity of commercial nitrite by titration. Theory: Sodium nitrite (commercial nitrite) solution is oxidized by potassium permanganate to nitrate: 2MnO4- + 6H+ + 5NO2- --> 2Mn2+ 5NO3- +3H2O As potassium permanganate itself changes colour in this reaction, so no indicator is required. However, once sodium nitrite is acidified, nitrous acid will form and decompose (*). Thus, sodium nitrite is placed in burette and added to acidified potassium permanganate. *2NaNO2 + H2SO4 -->Na2SO4 + 2HNO2 3HNO2-->HNO3 + H2O + 2NO Experimental procedure: 1. Around ( (should be a little more for the impurity)) 0.90g sodium nitrite powder was transferred and weighed to the nearest 0.01g in a weighting bottle. ...read more.

Middle

Data Trial 1st 2nd 3rd Initial reading (cm3) 0.20 0.00 0.06 12.34 Final reading (cm3) 25.20 25.00 25.08 37.40 Titre(cm3) 25.00 25.00 25.02 25.06 Mean titre: Calculation: Mol of titre used: As only 25.02cm3 titre was used for titration, mol of the total 250cm3 sodium nitrite solution: Thus, there is pure sodium nitrite: Finally, the purity of the commercial nitrite: Result: The purity of the commercial nitrite is 95.8% Discussion: The purity was found. There was just a small difference between the reference answer (94%) and the answer calculated. The 3rd time reading was larger than the previous readings due to the slow reaction of this experiment. Thus more sodium nitrite solution was added and might affect the result. ...read more.

Conclusion

When HNO3 is added to KMnO4, NO2 is formed which is toxic. 4. In weakly acidic, weakly alkaline and neutral medium, KMnO4 reduces to form the brown solid MnO2 instead of Mn2+. Write the equation for this reduction. MnO4 + 4H+ + 4e- -->MnO2 +2H2O 5. Explain why neutral KMnO4 (aq) is seldom used in redox titration. It is because the colour change is not significant, and so it is hard to judge the end point. 6. Suggest one advantage and one disadvantage of using acidified KMnO4 in redox titration. The advantage of using acidified KMnO4 in redox titration is the great colour change and so it can be indicator itself. The disadvantage of it is that it cannot react with compound containing chloride ion or high concentration acid. Conclusion: After the experiment and calculation, the purity found is 95.8%. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Physical 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 AS and A Level Physical Chemistry essays

  1. Analysis of commercial vitamin C tablets

    Collagen fibre plays an important role in teeth, cartilage, skin, blood vessels, etc. A deficiency in vitamin C results in defective collagen, causing symptoms of scurvy, bleeding gum, loosen teeth, etc. Vitamin C also acts as a reducing agent in many metabolic processes, including synthesis of enzymes and hormones.

  2. Investigating the Rate of the Reaction between Bromide and Bromate Ions in Acid Solution

    so I can use the same equation as I did when varying the temperature without a catalyst (page 39) to find k: (Equation 3.7.1) The values for average time (t), k, , average temperature (T) and for the reactions taking place at different temperatures with Iron (III)

  1. A-level Practical Chemistry experiment - Estimation of available chlorine in a commercial bleaching solution.

    The crystals was addedinto the solution in the conical flask. 12. About 15 cm3 ethanoic acid (about 1 M) was added into the solution of conical flask.(Mesuring Cylinder was used.) 13. The burette was rinsed with the standard sodium thiosulphate solution.

  2. Investigating how concentration affects rate of reaction

    1M Phenol solution Used as part of the reaction. 0.0001M Methyl orange indicator Used to show colour change in the reaction as phenol binding sites are used up by bromine. n/a Potassium bromide Used as part of the reaction. 0.01M Distilled water Used to dilute solutions to chosen concentrations.

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