Question

1. A student obtained the following results from the spectroscopy and titration experiments: 26.80% en, 16.01% Ni2+, 26.20% SO4 2- , 30.99%H2O. Use this information to determine the empirical formula of the unknown complex nickel salt. (Remember that the calculations are based on data, so the mole ratios may not come out perfect…what should you do in this case?)

Answer 1

Assume that the mass of the unknown complex is 100 g Mass of ethylenediamine en) 26.80 g 26.80 g 60.22 g/mol Moles of enmass of en = 0.4450 mol molar mass of en Mass ofNi216.01 g mass of Ni2+ atomic mass of Ni 16.01 g 58.69 g/mol Moles of N产- -= 0.2728 mol Mass ofSO-= 26.20 g Moles of so^mass of so Mass ofH230.99 g Moles of H2O Mole ratios is mol Ni2 mol en mol H,O mol SO0.2728 mol:0.4450 mol 1.720 mol: 0.2727 mol Divide with 0.2727 mol Ni2- :mol en mol H.O : mol sO mol Ni2- : mol en mol H,O : mol SO* - 1 mol: 2 mol: 6 mol: 1 mol So, the empirical formula 1:Ni( en )2 (HO)6 so, 26.20 g -0 2727 mol atomic mass ofSO96.06 g/mol mass of H,O 30.99 1.720 mol atomic mass of HO18.02 g/mol 0.2728 mol 0.4450 mo 1.720 mol 0.2727 mol 0.2727 0.2727 0.2727 0.2727