Jum University Science Books resented by Saping Leaming Gene

Jum University Science Books resented by Saping Leaming General Chemistry 4th Edhoe- The amount of ls (aq) in a solution can be determined by titration with a solution containing a known concentration of S0 (aq) (thiosulfate ion). The determination is based on the net ionic equation Given that k requires 30 3 ml of 0 470 M Na,s/Olag) to titrate a 25 0-mL sample of l, (aq), calculate the molarity of s (aq) in the solution )/ Hint

Solution

Number of moles of Na2S2O3 = molarity * volume of solution in L

Number of moles of Na2S2O3 = 0.470 * 0.0303 = 0.0142 mole

from the balanced equation we can say that

2 mole of Na2S2O3 requires 1 mole of I₃-so

0.0142 mole of Na2S2O3 will require

= 0.0142 mole of Na2S2O3 *( 1 mole of I₃- / 2 mole of Na2S2O3)

= 0.00710 mole of I₃^-

molarity of  I₃^- = number of moles of  I₃^- / volume of solution in L

molarity of  I₃^- = 0.00710 / 0.025 = 0.284 M

Therefore, molarity of I₃^- =0.284 M