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

Determination of the Number of Water of Crystallization in Oxalic Acid Crystals

Extracts from this document...


Determination of the Number of Water of Crystallization in Oxalic Acid Crystals Objective To determine the number of water of crystallization in a given sample of oxalic acid crystals by redox titration. There are two parts of experiment. In the first part, the determination of the concentration of a given potassium permanganate solution using a standard sodium oxalate solution by titration is expected. In the second part of the experiment, the aim is to work out the number of water of crystallization of hydrated oxalic acid based on data obtained from a titration experiment. Introduction This experiment concerns a redox titration. A given solution of potassium permanganate is standardized using a standard solution of sodium oxalate. A solution of hydrated oxalic acid is prepared and is titrated against the standardized potassium permanganate solution. An indicator is not required since a negligible excess of KMnO4 solution turns the contents of the conical flask from colourless to slight pink that marks the end-point. 2MnO4-(aq) + 16H+(aq) + 5C2O42-(aq) � 2Mn2+(aq) + 10CO2(g) + 8H2O(l) Experimental Procedure Part I Standardization of potassium permanganate 1. 25cm3 of the standard solution of Na2C2O4 is transferred into a conical flask and approximately equal volume of dilute H2SO4 is added to provide H+(aq) ...read more.


Trial 1 2 3 Final burette readings /cm3 26.79 28.48 27.59 26.94 Initial burette readings /cm3 2.36 4.32 3.31 2.82 Volume used /cm3 24.43 24.16 24.28 24.12 Mean titre /cm3 24.19 Calculation 2MnO4-(aq) + 16H+(aq) + 5C2O42-(aq) --> 2Mn2+(aq) + 10CO2(g) + 8H2O(l) 1) From result in Part (A), calculate the concentration of the given solution of KMnO4. Let M be the molarity of the given solution of KMnO4 ? The concentration of the given solution of KMnO4 is 0.0200 mol dm-3 2) From results in Part (B), calculate the number of moles of oxalic acid in 250 cm3 solution No. of moles of oxalic acid in 250 cm3 = 0.0121 mol Let M be the molarity of the oxalic acid ? The concentration of the oxalic acid is 0.0484 mol dm-3 3) Calculate the number of water of crystallization of hydrated oxalic acid, i.e., the value of n the formula H2C2O4.nH2O. Conclusion ?The formula of hydrated oxalic acid is H2C2O4.nH2O Question 1) In step 1 of part (A), the volume of sulphuric acid added was not precisely known. How would this affect the experimental result? Explain your answer. ...read more.


The disadvantage of this weighing method is that the sample will have contact with an intermediate container (i.e. weighing paper) and, therefore, there are chances of losing some solid in the transfer process. Thus, the oxalic acid crystals should be weighed directly in the beaker. This technique also avoids spills on the balance pan since the transfer process can be done outside the balance case. During the titration process, some potassium permanganate solution may be carelessly left in the inner wall of the conical flask while swirling. This would lead to overestimation of the volume of potassium permanganate solution required for the reactions. Thus, the burette tip should be inserted into a more inner position of the conical flask during titration. After obtaining the potassium permanganate solution, the solution was left in the beaker throughout the whole experiment. The experiment lasted for a long time and the potassium permanganate might have been decomposing slowly. This would make the molarity of the solution lower than that calculated in Part I. In order to avoid this, the potassium permanganate can be stored in a brown bottle after obtaining. Reference 1. Disodium oxalate - http://en.wikipedia.org/wiki/Sodium_oxalate 2. Potassium permanganate - http://en.wikipedia.org/wiki/Potassium_permanganate 3. How to Reduce Potassium Permanganate - http://www.ehow.com/how_5243407_reduce-potassium-permanganate.html 4. Preparation of a Standard Solution - http://eclass.ssc.edu.hk/inabox/files/c20/reference/4f6149b8730f80f37f04338f6fe7b451_1235373694AL%20Chemistry/AL%20Chemistry/Lab%20Manuals/Form%206/F6_09lab01_Standard_Solution.pdf ...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. Acid-base titration. Objective To determine the concentration of sulphuric acid (H2SO4) using sodium ...

    For what reasons should the weighing process be carried out as quickly as possible if filter paper instead of weighing bottle is to used? -It is to avoid absorption of moisture from the atmosphere to the filter paper 3.

  2. Determination of the Percentage of Oxalate in Iron(II) Oxalate by Redox Titration

    A few drops of potassium permanganate were added to the conical flask. The flask was shaken until a yellow colour appeared. 9. Potassium permanganate was further added until the solution turned pink. The reading was taken. 10. Steps 5 to 9 was repeated 3 more times.

  1. Drug: Antacid Effectiveness Analysis To determine the neutralizing ability of antacids in different ...

    Improvements 1. Sufficient time should be given for the reaction of acid and base. 2. pH metre should be used to detect the end point. 1. Why do we use back titration instead of acid/base titration? Acid/ base titration is very difficult because the active ingredient is only sparingly soluble in water.

  2. Determination of the content of Mg (OH)2 in an indigestion remedy by back titration ...

    % error = 0.001g/mass measured x 100 Average weight of mass measured (4.118g + 4.708g + 4.399g/3) = 4.408g (3.d.p) 0.001g/4.408g x 100 = 0.023%. % Error of Pipette % error = 0.1cm3 /25cm3 x100 = 0.4% % Error of Burette % error = 0.05cm3 /50cm3 x100 = 0.1% %

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

    of solution to find the order of the reaction with respect to each of the reactants (see above - page 8). I will then choose set concentrations of each reactant and measure the time taken for the methyl orange to change colour with different temperatures.

  2. Acid-Base Titrations.

    Na+ + OH- + H3O+ + CH3COO- --> H2O + Na+ + CH3COO-. The reaction stoichiometry is 1:1 in both cases. The pH change can be detected by a pH meter, an electrochemical device whose discussion we will defer to later sections, or by a chemical indicator.

  1. The Determination of rate equation

    The cross will act as the indicator for the experiment, the solution will be placed on top of the cross to measure the rate of reaction, and we will time using a stop watch how long it takes for the solution to become cloudy and the cross to disappear through the solution from the birds eye view.

  2. How does the temperature of water affect the amount of dissolved oxygen it contains?

    salt, iodide (I-) and hydroxide (OH-) ions is added to a water sample causing a white precipitate of Mn(OH)2 to form. This precipitate is then oxidized by the dissolved oxygen in the water sample into a brown manganese precipitate. In the next step, sulphuric acid is added to acidify the solution resulting in Mn(SO4)2, (a brown precipitate).

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