Answer to Question #136782 in General Chemistry for Lupi Perez

Question

What is the molar concentration of Fe2+ ion in an aqueous solution if 35.50 mL of 0.113 M KBrO3 is required for complete reaction with 13.00 mL of the Fe2+ solution? The net ionic equation is:
6Fe2+(aq)+BrO3−(aq)+6H+(aq)→6Fe3+(aq)+Br−(aq)+3H2O(l).

Answer 1

Solution:

For redox reaction

M₁ × n₁ × V₁ = M₂ × n₂ × V₂ 

M - molarity

M Fe²⁺ × n Fe²⁺ × V Fe²⁺ = M KBrO₃ × n KBrO₃ × V KBrO₃

For the following reaction calculate molarity M Fe²⁺

n of KBrO₃ = 1; n of Fe ²⁺ = 1/6

M Fe ²⁺ = M KBrO₃ × n KBrO₃ × V KBrO₃ / n Fe²⁺ × V Fe²⁺ = 0.113×1×35.50 / 1/6×13.0 = 1.85M

Answer: Molarity of the Fe²⁺ solution is 1.85M.