Question

When 10 mL of an aqueous solution of Fe²⁺ ions was titrated in the presence of dil H₂SO₄ using diphenylamine indicator, 15 mL of 0.02 M solution of K₂Cr₂O₇ was required to get the end point. The molarity of the solution containing Fe²⁺ ions is X x 10^–2 M. The value of x is ......... (Nearest integer) 

Answer 1

milli-equivalents of Fe²⁺ = milli-equivalents of K₂Cr₂O₇ 

M × 10 × 1 = 0.02 × 15 × 6 

M = 0.18 = 18 × 10^–2 M