These questions are based on Complex-Compounds equilibriums and titrations (This involves EDTA)
THERE ARE 8 QUESTIONS ONLY TO BE ANSWERED B1-B8
I need you to help me answer them in a way I can understand how to do it myself. There are some I am able to do on my own but some confuse me. Please do it in a way indicating the question number, the data given by the question, the data we need to compute, and the formulas and steps for computing the data.
All reactions must be written down and answers must be orderly ad understandable
The document provided is in Spanish (please just copy paste the questions into google translate, I can also translate them for you if you choose to accept this answer request) but you can answer in English.
B.1.- A) Show that it is possible to determine the content of Cd (II) and Mg (II) of a solution, by titration of two aliquots with EDTA 0.01 M: a) at pH 4.0 in acetic medium / acetate, and b) at pH 10.0 in the presence of 0.1 M free cyanide
B) If the volume of EDTA consumed in the titration of a 50.0 mL aliquot of both ions at pH 4.0 is 35.0 mL and that consumed to titrate a second 50.0 mL aliquot at pH 10.0 in the presence of 0.1M free cyanide, it is of 15.0 mL, calculate the concentration of the metal ions in the initial solution.
B.2.- Why is the use of conditional constants necessary in the treatment of complex formation equilibrium? What meaning do they have? How are they calculated?
Apply to a Fe (III) solution that reacts with EDTA at pH 5.0 in the presence of 0.1 M sodium fluoride.
B.3.- Reasonably justify whether the following statements are true or false:
a) A labile complex is characterized by its high stability.
b) EDTA forms complexes whose stoichiometry depends on the charge of the metal ion with the
what a complex way
c) The global formation constant (?n) of the MLn complex is equal to ?? = ?? ?? …. ?? ? ???
d) In the conditional formation constant K ’of a complex MLn, the concentration [M]’ is the
total concentration of metal ion that has not reacted with ligand L.
e) The conditional formation constant of complexes with EDTA increases with increasing
pH of the medium.
B.4.- Study the possibility of carrying out the titration of 50.0 mL of a solution containing Mg2 + 0.01 M with EDTA of the same concentration in ammonium / ammonia regulating medium of pH 10.0. What is the fraction of unvalued (free) species at the equivalence point?
B5.
A solution contains a mixture of Co2 + and Ni2 +. To determine both ions, a two-stage procedure is applied:
A) First, a 1.0 mL aliquot is taken and 25.0 mL of a 0.03872 M EDTA solution of pH 5.0 is added. Next, the previous solution is titrated with 23.5 mL of a Zn2 + 0.02127 M solution.
B) In another 2.0 mL aliquot of sample, the Co2 + is separated, and the remaining Ni2 + is treated with 25.0 mL of 0.03872 M EDTA and titrated with the Zn2 + solution, spending 25.6 mL.
It asks:
a) Justify the procedure used, and using the data that appear at the end of the statement, demonstrate that it is not possible to carry out the determination of Ni2 + directly in the mixture without interfering with Co2 +.
b) Calculate the concentration of both ions expressed in mg / mL.
B.6.- Calculate the free concentrations of Fe3 + and Y4- in a solution of pH = 4.0 that initially contains concentrations 10-3 M and 0.1 M, respectively, of both species.
B.7.- A standard solution of EDTA, of which 10.0 ml is equivalent to 31.8 mg of HgO, was used to determine the mercury content in 1,500 g of the diuretic Metalluride (C16H21HgN6NaO7). For this, the solid sample was properly treated, and the inorganic residue was titrated with 41.1 ml of EDTA. It asks:
a) Using the data at the end of the statement, show that it is possible to carry out the Hg (II) titration with EDTA at pH 2.
b) Calculate the molarity of the EDTA solution
c) Calculate the concentration of mercury in the sample expressed as mg / g of HgO
B.8.- Calamine, which is used to relieve skin irritations, contains zinc oxide and ferric oxide. A 0.222 g sample of dried calamine is dissolved in acid and diluted to 250 mL. Potassium fluoride is added to a 50.0 mL aliquot of the solution to mask the iron and, after the appropriate pH adjustment, it is titrated with EDTA at a concentration of 0.0129 M, consuming 30 mL. An excess of ZnY2- complex is added to a second 50.0 mL aliquot at the appropriate pH. Next, all the Zn2 + contained in the resulting solution is titrated with 0.0129 M EDTA, spending 34.0 mL. It asks:
a) Write all the reactions involved, justifying the procedure followed. b) Calculate the percentages of zinc oxide and ferric oxide in the sample.
0 comments