After synthesizing the complex K w [Fe x (C 2 O 4 ) y ] * zH 2 O, a student titr
ID: 791370 • Letter: A
Question
After synthesizing the complex Kw[Fex(C2O4)y]*zH2O, a student titrates 0.100 g of the complex with a KMnO4 solution (first balance and then answer)
MnO4- + H2C2O4 + H+ --> Mn2+ + CO2 + H2O
a. What is the percent of C2O42- in the complex
b. If the concentration of iron (III) is found to be 0.03258 M in 10.0 mL of solution ( where the solution = 0.100 gram of complex + 10 mL of water) what is the % of iron (III) in the complex?
c. Calculate the whole number ratio of Iron (III) ions to Oxalate ions in the complex.
d. To have a neutral complex how many potassium ions must there be in the formula of the complex?
e. What is the empirical formula of the complex, leaving out the water of hydration
f. What is the molecular formula of the complex if the molar mass is 613.8
Explanation / Answer
MnO4- + H2C2O4+ H+--> Mn2++ CO2+ H2O
2 MnO4- (aq ) + 5 C2O4-2 (aq ) + 16 H+ (aq ) ----> 2 Mn2+ (aq) + 10 CO2 (g ) + 8 H2O (l)
balanced reaction
Two moles of Permanganate will react with 5 moles of Oxalate.
molar maass of kmno4 is 158 gm/mol
moles of kmno4 in the reaction = 0.1/158 = 6.33*10^-4 moles
one mole of Permanganate will react with 5/2 moles of Oxalate.
6.33*10^-4 moles of Permanganate will react with 2.5*6.33*10^-4 moles = 1.58*10^-3 of Oxalate.
88,01 g/mole *1.58*10^-3 moles = 0,1392 grams of Oxalate is present.
1)
This is 0,1392 grams /2* 0,1 grams of complex * 100 =69.62 % .-
If the concentration of iron (III) is found to be 0.03258 M in 10.0 mL of solution ( where the solution = 0.100 gram of complex + 10 mL of water) what is the % of iron (III) in the complex?
mass of iron = 0.03258*0.01 = 0.003258 moles *55.8 = 0.1817 gms
complex weight = 100*0.01 = 10 *0.1 = 1gm
2 )iron percentage = 0.1817/1 *100 =18.17%
3)
c. Calculate the whole number ratio of Iron (III) ions to Oxalate ions in the complex.
that is 1:3
Kw[Fex(C2O4)y]*zH2O== K3[Fe1(C2O4)3]*8H2O
d. To have a neutral complex how many potassium ions must there be in the formula of the complex?
3 because here K3 is there in the formuila
e. What is the empirical formula of the complex, leaving out the water of hydration
K3[Fe1(C2O4)3]
f. What is the molecular formula of the complex if the molar mass is 613.8
K3[Fe1(C2O4)3]*10H2O