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

FInding the percentage purity of CACO3 in egg shell

Extracts from this document...

Introduction

Aim Egg shell is hard and cracks easily when beaten because of the constituent of CaCO3.Our main aim will be to determine the purity or the percentage composition of CaCO3 in the egg shell by using the technique of back titration. The egg shell is just a representation of any substance containing CaCO3 in their constitution; this method could be used to find the percentage purity of marble, limestone, sea shell etc. Identification of Variables Independent variable 1. Purity of CaCO3 in the egg shell Dependent Variable 1. Volume of Hcl Controlled Variable 1. Concentration of Hcl The concentration of Hcl that is going to be used must be calculated for the experiment for show results. I took 4.931 g of egg shell which is 0.04931 moles. We will be following the procedure of back titration in this experiment since CaCO3is insoluble in water/reacts slowly with acid. Thus the first procedure of back titration is to react the substance with excess of acid , which means that we have to take a slightly high concentration of a preferred acid , in this experiment we have taken 2M of Hcl acid. ...read more.

Middle

16. Now pour the solution of egg shell and acid from the beaker in to the glass funnel carefully. 17. The solution is being filtered , it will take time. 18. The solution will not however add up to 250cm3 volume, so we need to add distilled water into the volumetric flask. Make sure that the water that is added stays under the filter paper level so as that it is being filtered. 19. After the solution has reached the 250cm3 , take a stirrer bar drop it in the volumetric flask , put the flask on the stirrer and let the solution stir for 2 hours. 20. Now take a pipette, make sure that the pipette is clean. 21. Rinse the pipette 22. Take a conical flask of 250cm3 and rinse it. 23. Using the pipette transfer the solution into the conical flask. 24. Take a burette and rinse it with NaOH , the desired alkali. 25. Put the plastic funnel on top of the beaker and carefully pour the alkali into the beaker. 26. Make sure that the meniscus is just above the zero mark. ...read more.

Conclusion

Back titration is a titration done in reverse; instead of titrating the original sample, a known excess of standard reagent is added to the solution, and the excess is titrated. A back titration is useful if the endpoint of the reverse titration is easier to identify than the endpoint of the normal titration, as with precipitation reactions. Back titrations are also useful if the reaction between the analyte and the titrate is very slow, or when the analyte is in a non-soluble solid. First measured mass of egg shell was taken and it was reacted with excess of HCl acid in a beaker. The solution was then taken and the volume was increased to 250cm3.Then using a pipette 25cm3 volume of the solution was taken and was poured into a volumetric flask and it was titrated against a known concentration of NaOH.This was repeated 7 times and the mean titre was found to be 21.11cm3. After finding the titre calculations were done to find the mass of CaCO3 present in the egg shell. The egg shell weighed 4.931 g ± 0.001 and was found to contain 4.750 g ± 0.1653 g CaCO3 . The % purity of the egg shell containing CaCO3 was found by using the give formula :- (Mass of CaCO3/Mass of egg shell) x 100 which gave 96.32% purity. ...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

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. A comparison of various proprieary antacids

    �0.05 cm3 0.00 0.00 0.00 Volume of NaOH �0.1 cm3 1.45 1.20 1.30 Closest Results Colour change of mixture in conical flask Cloudy white--> Milky Pink Volume of HCl(aq) used per trial= 25cm3 � 0.05 cm3 Table 2: Showing the volumes of Sodium hydroxide base(0.5 M)

  2. Back Titration - Percentage Fertilizer

    This required great precision and allowed a decent margin of error if not taken with patience.

  1. Enthalpy Change Design Lab (6/6)How does changing the initial temperature (19C, 25C, 35C, and ...

    To ensure the rate of reaction between the 40.0 cm3 of 1.00 mol dm-3 KOH(aq) and 40.0 cm3 of 1.00 mol dm-3 HCl(aq) is as fast as possible, an electrically powered magnetic stirrer, and magnetic bar will be used for each variation in temperature, and each subsequent trial to agitate the solutions and speed the reaction.

  2. Design Lab, HCl + Marble chips

    required (for 1 trial): 50mL Concentration required: 1.0M Concentration in-hand: 3.0M C1V1=C2V2 (3.00)(x) = (1.00)(50) x = 16.7mL of 3.0M of HCL and 33.3mL (50 - 16.7) of distilled water. 1.00M of HCl= 16.7mL of 3.0M of HCL + 33.3mL of distilled water This prepares 1.00M of HCl Similarly, prepare

  1. Calculate % of caco3 in white egg shell

    Using a graduated pipette add 20.0cm3 of 1.00moldm-3 of hydrochloric acid slowly any swirl the flask to prevent any small amount from escaping from the flask with the carbon dioxide that is produced. 2. Once the reaction is completed add about 20 cm3 of distilled water and transfer all

  2. Finding thr Percentage Composition of Magnesium Oxide

    Answer the Testable Question that was posed at the beginning of this investigation. Support your answer with evidence.

  1. The use of volumetric flask, burette and pipette in determining the concentration of NaOH ...

    20.0cm3 of acid solution was pipette into three clean Erlenmeyer flasks. 7. Two drops of phenolphthalein was added into the acid solution. 8. The initial burette reading was recorded and the acid solution was titrated with NaOH solution in the burette until the end point was reached.

  2. Chemistry Titration Acid Base Lab

    Concentration of Acetic Acid Before Dilution = 0.9mol/dm3 Sample Calculation B: Calculating Percent Uncertainty for the Volume of Sodium Hydroxide Needed for Different Indicators Example: Bromocresol Green =× =25.0% Sample Calculation C: Calculating the Percent Error Percent error )×100 )

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