In a previous

experiment, 0.800 g of the green complex iron salt was placed in an Erlenmeyer flask and
heated with concentrated sulfuric acid until all oxalate ion was destroyed (CO2, SO2 and
H2O are formed). Ferric ion (Fe3+) remained in solution and was reduced to Fe2+ by reaction
with Al wire. The ferrous ion (Fe2+) was then titrated with KMnO4 solution according to
equation (2) and 32.60 mL of 0.0100 M permanganate solution was required to reach the
endpoint. The blank required 0.03 mL of the permanganate solution. Find the mass % of
iron in the complex salt.

moles KMnO4 = M x L

Using the coefficients in the balanced equation, convert moles KMnO4 to moles Fe^+2.
Convert moles Fe to grams. grams = moles x molar mass.

%Fe = (g Fe/0.8)*100 = ??
NOte that there is a blank of 0.03 mL; therefore, the volume of KMnO4 is 32.60 mL - 0.03 mL and convert that answer to L for the M x L equation above. Note also that the Fe + KMnO4 equation above is not balanced.

Equation 2 is Fe2+ (aq) + MnO4

–(aq) 􀃆 Fe3+(aq) + Mn2+(aq)

Concentration of KMnO4 is 0.0082003124

To find the mass percentage of iron in the complex salt, we need to follow a step-by-step process:

Step 1: Calculate the number of moles of KMnO4 used in the titration.
The volume of KMnO4 solution required to reach the endpoint is 32.60 mL. The molarity of the KMnO4 solution is 0.0100 M. Using the equation Molarity (M) = Moles (mol) / Volume (L), we can calculate the moles of KMnO4 used:

Moles KMnO4 = Molarity KMnO4 × Volume KMnO4
= 0.0100 mol/L × 0.03260 L

Step 2: Calculate the number of moles of Fe2+ in the complex salt.
According to equation (2), the stoichiometry between Fe2+ and KMnO4 is 5:1. This means that for every 5 moles of Fe2+, 1 mole of KMnO4 is consumed.

Moles Fe2+ = Moles KMnO4 × (5 moles Fe2+ / 1 mole KMnO4)

Step 3: Calculate the molar mass of Fe2+.
The molar mass of Fe2+ can be calculated by summing the atomic masses of iron (Fe).

Molar mass Fe2+ = Atomic mass Fe

Step 4: Calculate the mass of Fe2+ in the complex salt.
To calculate the mass of Fe2+ in the complex salt, we can use the equation: Mass Fe2+ = Moles Fe2+ × Molar mass Fe2+

Step 5: Calculate the mass percentage of iron in the complex salt.
The mass percentage of iron can be calculated using the equation: Mass % Fe = (Mass Fe2+ / Mass of complex salt) × 100%

Given:
Mass of green complex iron salt = 0.800 g
Volume of blank KMnO4 solution = 0.03 mL (0.030 mL)
Molarity of KMnO4 solution = 0.0100 M

Now, let's plug in the values and calculate step by step:

Step 1:
Moles KMnO4 = 0.0100 mol/L × 0.03260 L = 0.000326 mol KMnO4

Step 2:
Moles Fe2+ = 0.000326 mol KMnO4 × (5 moles Fe2+ / 1 mole KMnO4) = 0.00163 mol Fe2+

Step 3:
Molar mass Fe2+ = Atomic mass Fe = 55.845 g/mol (from the periodic table)

Step 4:
Mass Fe2+ = 0.00163 mol Fe2+ × 55.845 g/mol = 0.0903 g Fe2+

Step 5:
Mass % Fe = (0.0903 g Fe2+ / 0.800 g complex salt) × 100% = 11.2875%

Therefore, the mass percentage of iron in the green complex iron salt is approximately 11.29%.