Question

10.5 Zn and Ni?' both react quantitatively with EDTA (Y) Zn2+ + Y4 → ZnY- Ni2+ + + + NIY The reagent 2,3-dimercapto-1-propanol (Z) reacts with the zinc-EDTA complex to liberate EDTA but it does not react with the nickel-EDTA complex. ZnY + Z - ZnZ+Y4 NiY+Z-NR. 50.00 mL of a sample solution that contains Ni and Zn? are mixed with 50.00 mL of 0.01981 M EDTA. The excess EDTA is titrated with 0.02010 M Mg, requiring 12.42 mL. Then, 15 mL of 0.10 M 2,3-dimercapto-1-propanol are added. The resulting solution is titrated again with 0.02010 M Mg?, requiring 18.94 mL. Calculate the molarity of Zn*and Ni" in the sample solution. (0.007614 M, 0.007203 M)

Answer 1

mixlone VSlution So 00 mL Vot ume of N and 22 Volume of EDTA added Molaity Concentralion of EDTA 0.01981M Given SO.00ml CVem) Rmalar rah'o veautions There all seachons ahe Nole : Moles of EDT added MEDTAX VeDTA (neDm) C 0.0198) MX So.00mL O.9905 mmel Noco, we hare to colcdaled tea moles o excen EDEA totee Solution Concontation of Ma Volume ol Mat rered 12.42 ml 0.02010 M 2t Mcefuired = moles of excess EDTA tee sclute moles of =Magt XVgir 0.02010 Mx1242 m O.249642 mmol meles of exces GDTA o tee Solution = So9 O.949642 anel TEDTA,exco8 Hend moles of Ni2t 2 znt (matnt)meDTAEDTA, excet 10.9905-0.24964)me -0 Nos సంబి = 0.44085S8 mmel Ae t is qiven teat 2,2dimercapto -ppanal (2) reocts wite Zn-EDTA Volume of z added Concentedion ofz meles of zaddes 0.3oM (-M) M2XV 0.10MYLSML-1.5mmol awre aadad tn excess)

EDTA Comes trom te reaction of z tth Zn-eDTA Sos Cormplex ustich x dbrated sth Mg Concentndion of M(Mn Volume ol Mgt usod (Ue) 18-34m 0.02010M used- Mmt xUngi moles of Mt = 0.02010M x 1894ul 0.38 0694 mmol melas of EDTA cmn tom 2n-E DTA Complex -molas of Matused = 0.380694 mmel Sos mdles of Zn2 ea solutlon O. 380694 mmal = 0.380694 mmol rorm =0.+140858 mmot 2 t NT 0t40858-n20t = (0.t40858-o.380694)mmel Nit0.360o164 mmel 0.380694 mmol m2nt melerity of Zn (M) So.00 mb Vealutin = 0-00-+61388 mol /L 0.001614 M or M O.360164 mmot meluaty of Ni(Ma2) Vsolution 50.00ml 0.00120328 malll 20.001203 M