The percentage by mass of iron in a steel wire is determined by a student.
The student:
Give the equation for the reaction between iron and sulfuric acid.
The titration results are shown in Table 1.
| 1 | 2 | 3 | |
|---|---|---|---|
| Final volume / cm3\text{cm}^3cm3 | 23.90 | 46.80 | 22.80 |
| Initial volume / cm3\text{cm}^3cm3 | 0.00 | 23.90 | 0.00 |
| Titre / cm3\text{cm}^3cm3 | 23.90 | 22.90 | 22.80 |
Calculate the mean titre.
Give the overall ionic equation for the oxidation of Fe2+\text{Fe}^{2+}Fe2+ by manganate(VII) ions, MnO4−\text{MnO}_4^-MnO4−, in acidic conditions.
State the colour change seen at the end point of the titration.
Name the piece of apparatus used for these stages of the method.
The balance used to weigh the 800 mg800\text{ mg}800 mg of iron wire has an uncertainty of ±0.005 g\pm 0.005\text{ g}±0.005 g. A container was weighed and its mass was subtracted from the total mass of the container and wire. Calculate the percentage uncertainty in using the balance. Give your answer to two decimal places.
