Question

Suppose a student needs to standardize a sodium thiosulfate, Na, S, O3, solution for a titration experiment. To do so, he or she will react it with a solution of iodine. The student adds a 1.00 mL aliquot of 0.0200 M KIO, solution to a flask, followed by 3 mL of distilled water, 0.2 g of solid KI, and 1 mL H, SO . The student then titrates the solution with sodium thiosulfate solution in order to determine the exact concentration of Na,s,o,. The end point of the titration is reached after 0.83 mL of Na,s,o, is dispensed from a microburet. What is the concentration of the standard sodium thiosulfate solution? concentration =

Answer 1

reaction is as follow resction-1 I š +52 +6H+ 3Ig + 2H₂O -2 Iq + 25,03 -→ 21+ 5408 ImL=0.0012 Initial mol g KIO3 = Molareily xvolume L) = 0. Dolk X D0200 mol = 0.00002 mol

man g K1 = 0.29 mol og Kd = 0.29 ,0.00120 mol 166. g 1 molt 5 mol of I react with Imol 105 0.00l2o mol of a react with 0.000a4 mol 105 But mol of 103 = 0.0000 a mol 205 is limting reagent and consume completely and molg te Zg fromed according to 10% I mol 105 give 3 mo Ta 0.000og mol Jor give o.oooo6 mol I a JE mol g 19 = 0.00006 de la 200 I mol Iq react 2 mol of S₂ 03 0.00006 mol La react 0.ooola mol of S203 mol og 5,03 react = 0.00012 mol volume = 0.85m2 = 0.00085L Molarity of 5,0% = 0.0002 mol = 0.141m 0.000852 Molaring g 5,0z= 0.14 m (in two significant Anna Figur)