25 ~mL of 0.08 ~N Mohr salt solution is oxidised by 20 ~mL of K ₂ Cr ₂ O ₇ in acid medium. The mass of Mohr's sallt present in 500 cc is

Step-by-step solution

The reaction of Miohr's salt and K ₂ Cr ₂ O ₇ is as follow: 6 Fe ²⁺+ Cr ₂ O ₇²⁻+14 [ H ⁺ ] 6 Fe ³⁺+2 Cr ³⁺+7 H ₂ O n -factor of Cr ₂ O ₇²⁻ is 6 and n -factor of Fe ²⁺ is 1 . As n -factor for Fe is 1 so, Molarity = Normality Concentration of Mohr's salt =0.08 M Moles in 25 ~mL of 0.08 M Mohr's salt =0.08 25 1000 =0.002 Moles in 500 cc of Mohr's salt =0.002 500 25 =0.04 Hence, mass of Mohr's salt in 500 cc =0.04 392=15.68 ~g