Ib Lab Report - Iron Tablets

LAB REPORT – IRON TABLETS

DATA COLLECTION

Iron tablets: 2.06 g ± 0.01
Sulphuric acid: 100 ml ± 1

Initial reading /cm3 (±0.1) Final reading /cm3 (±0.1) Titre /cm3 (±0.2)
Rough 2.8 22.319.5
Run 1 22.3 41.6 19.3

First we need to state an equation for the reaction between MnO4- and Fe2+.
Using the know equation:
Fe2+(aq) ----- Fe3+(aq) + e- we multiply it times five so that we get5Fe2+(aq) ----- 5Fe3+(aq) + 5e-

Now we add that to the equation given:
MnO4-(aq) + 8H(aq) + 5e- ----- Mn2+(aq) + 4H2O(l)
And we get:
MnO4-(aq) + 8H(aq) + 5Fe2+ ----- Mn2+(aq) + 5Fe3+ +4H2O(l)

First we calculate the number of moles of MnO4 that were used in the experiment.
% error = (0.2 x 100) / 19.3 = 1.0%
# Moles = (Concentration x Volume) / 1000
# Moles = (0.01 x 19.3±1.0%) /1000
# Moles = 1.93 x 10-4 ±1.0%

Now to calculate the moles of Fe2+ that where in 25 cm3 we use the equation and the ratio of moles that reacts together.
(1.93 x 10-4 ±1.0%) x 5 = 9.65 x 10-4±1.0%

We time the value times 10 to get the moles in a 250cm3 solution
(9.65 x 10-4 ±1.0%) x10 = 9.65 x 10-3 ±1.0%

Now we calculate the mass used by using the following formula:
Mass = moles x ArAr of Fe = 55.85
Mass = (9.65 x 10-3 ±1.0%) x 55.85
Mass = 0.54 ± 1.0% grams

Finally we calculate the percentage that this vale represents in the initial amount of iron tablets.
% error =(0.01 x100) / 2.06 = 0.46 %
(0.54 ± 1.0%) / (2.06 ± 0.46%) x 100 = 26.21 % ± 1.46%

QUALITATIVE DATA
• The iron tablets did not dissolve completely while heating the sulphuric acid; there wheresmall pieces floating around.
• When heating the sulphuric acid with the iron tablets a smell was produced and some gas was coming out of the conical flask.
• Due to the darkness of the potassiummanganate (VII) solution and difficulty to be accurate enough the readings in the titration have an uncertainty of ±0.1 cm3 instead of the normal ±0.05 cm3.

CONCLUSION

After the carrying out...