Question

For the following reaction between Mohr\'s salt (iron as FeSO4(NH4)2SO4·6H2O) and potassium dichromate (dichromate as K2Cr2O7), determine the volume (in milliliters) of a 0.100 M solution of Mohr\'s salt that is needed to fully react with 0.0800 L of 0.100 M potassium dichromate. (The reaction is shown in its ionic form in the presence of a strong acid.)

Cr2 O7^2- + 6Fe^2+ +14H^+ ------- 2Cr^3+ +6Fe^3+ +7H2O

For the same reaction, what volume (in milliliters) of 0.100 M potassium dichromate is required to fully react with 0.0800 L of a 0.100 M solution of Mohr\'s salt?

Answer 1

Cr2 O7^2- + 6Fe^2+ +14H^+ ------- 2Cr^3+ +6Fe^3+ +7H2O

1 mol Cr2 O7^2- = 6 mol Fe^2+

M1 = concentration of K2cR2o7 = 0.1 M   , M2 = concentration of mohrs salt = 0.1 M

V1 = vol of K2cR2o7 = 0.08 L     ,         V2 = vol of mohrs salt = ?

n1 = 1 ,                                   n2 = 6

M1V1/n1 = M2V2/n2

(0.1*0.08/1) = (0.1*V2/6)

V2 = vol of mohrs salt = 0.48 L

    = 480 ml

M1V1/n1 = M2V2/n2

(0.1*V1/1) = (0.1*0.08/6)

V1 = vol of K2CrO7 = 0.0133 L

    = 13.3 ml

V1 = vol of K2Cr2O7 = 13.3 ML