Answer:
The molarity is 0.203 M
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.
