Please help with analytical chemistry

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Please help with analytical chemistry

Post by Bruno »

I am struggling a lot with analytical chemistry and i really need help to solve this question.

A Cr3+ solution was prepared by dissolving 0.2525g of CrCl3.6H2O salt in 250 mL of 0.01 mol L-1 HCl. From this stock solution, a solution was prepared by diluting 21.3 mL of the stock solution in 50 mL of 0.01 mol L-1 HCl, adding a mass of EDTA sodium salt (Na2C10H12O8N2. 2H2O) necessary to the formation of the complex (calculate!). The solution was then heated to boiling temperature, changing colorless to violet, generating the Cr-EDTA complex. Thus: what is the concentration of free Cr3+ in solution, at equilibrium, after complexing with EDTA? Calculate the fraction of each of them. Then write the Cr3+ balance with each of these EDTA species present. Why was it necessary to warm up? The maximum absorption of the complex in the visible spectrum region occurs at 542nm. Calculate the energy per mole at this wavelength. Also calculate the electrostatic parameter of Cr3+, K of the EDTA-Cr complex = 2.51x10^23.
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Re: Please help with analytical chemistry

Post by ChenBeier »

Calculate the mole of Chrome trichloride hexa hydrate by using molar mass. This is equal of moles of Chrome III. This is dissolved in 250 ml. An aliquot 21.3 ml was taken. How much moles correspond to it and diluted to 50 ml. Get the concentration for it.
In my knowledge EDTA make a 1:1 COMPLEX. Maybe its different need some recherche. So you need the same moles of EDTA. Calculate the mass for it.
For the next questions you have to use the law of mass action.
K = ..... ... 7060801274
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