Question

tion 2 of 2 OAttempt 1 Suppose a student needs to standardize a sodium thiosulfate, Na, S, O,, 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 mlL 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 0.77 mL of Na, S,0, is dispensed from a microburet. What is the concentration of the standard sodium thiosulfate solution? concentration M .156

Answer 1

Anstes let, ne Yeaction between kios and ki acidic mediu Nel iouic Yeaction Tos 5 6t 3 + 3H20 Reactian betueen with thio Sulphate 2Nat Seos NaiSi03 ISuo 32 6523 Net Yea ction To3 +CHT6S20 35o sH2o Mole of Ios used molevity *volue (L) o.G2 Mo Imolcovol O0000 2 Mo 1 mole o eIos Yeact with 6 mol S2 03 O.oooo 2 mol kos eact uth o0o0)2 mol S203

S20Used mole of o.o0o12 md olumeo 7m Molarity Molavity NolumelL) O.Ooul 2 mol 7ttoco o 0 155 8 M There fore, O1553 M The molarity of Na2 Si03 is