Question

What is the molarity of a potassium triiodide solution, KI3(aq), if 30.00 mL of the solution is required to completely react with 25.00 mL of a 0.500 M thiosulfate solution, K2S2O3(aq)

Answer 1

The molarity is 0.203 M

Step-by-step explanation:

Using the formula C(oxi) x V(oxi) / [C(red) x V(red)] = N(oxi) / N(red)

Where oxi and red means reducing agent and oxidising agent respectively.

C = Concentration, V = Volume and N = number of moles.

C(oxi) = 0.5 M

V(oxi) = mL

C(red) = ?

V(red) = 30mL

Equation of reaction = 2K2S2O3 + KI3 = K2S4O6 + 3KI

so N(red) = 1 , N(oxi) = 2

from the equation above,

C(red) = 0.5 x 25 x 1 / (2 x 30)

= 0.203 M.