EDTA Calculation Watch
An alloy of chromel containing Ni,Fe & Cr was analysed by a complexometric titration using EDTA as the titrant. The solution of the alloy was prepared by dissolving 0.7176g of alloy in HNO3 and then diluted to mark in 250cm³ volumetric flask. 50cm³ of this aliquot of the sample was treated with pyrophosphate to mark the iron and chromium. If this aliquot of the sample require 26.14cm³ of 0.058M EDTA to reach the end point with murexide as the indicator. In a second titration 50cm³ aliquot treated with hexamethylenetetraamine to mask chromium require 35.43cm³ of 0.058M EDTA to reach the end point. Finally, a third 50cm³ of aliquot was treated 50cm³ of 0.058M EDTA and back titrated with 6.21cm³ of 0.063M Cu²+ yo reach the end point with murexide indicator. Calculate the percentage of Nickel, Iron and chromium in the alloy.
You need to work out how many moles of EDTA is in 26.14ml of 0.058M. Its a simple maths problem.