Answer:
[tex]\boxed{\text{0.017 mol/L}}[/tex]
Explanation:
Na₂S₂O₃ solution does not react with KI (it reacts with I₂), so it is simply diluting the KI, and we can use the dilution formula.
[tex]c_{1}V_{1} = c_{2}V_{2}[/tex]
Data:
c₁ = 0.15 mol·L⁻¹; V₁ = 5 drops
V(Na₂S₂O₃) = 40 drops
Calculations:
(a) Calculate the total volume
V₂ = 5 + 40 = 45 drops
(b) Calculate the concentration
0.15 × 5 = c₂ × 45
0.75 = 45c₂
[tex]c_{2} = \dfrac{0.75 }{45} = \boxed{\textbf{0.017 mol/L}}[/tex]
