Determining the iron content in a sample of steel wool Natalie Loo 12A
Aim:
To find the percentage of iron in a sample of steel wool.
Method:
- Weigh accurately about 1g of steel wool and add enough dilute sulphuric acid to cover it in a conical flask. Heat the flask gently until the reaction starts.
- When all the steel wool has dissolved, filter the solution and the washings from the flask into a beaker.
- Make the solution up to 250ml in a volumetric flask with boiled, cooled distilled water, washing the beaker out with boiled distilled water twice.
- Calculate the mass of KmnO4 needed to make up 500ml of 0.02M solution.
- Weigh out approximately this mass of solid KmnO4 and dissolve in 500ml of water in a 1L beaker.
- Cover the beaker with a watch glass and boil it for 10 minutes.
- Cool the solution and filter it through glass wool into a clean storage bottle. Label the bottle.
- Calculate the mass of oxalic acid needed to make up 250ml of 0.05M solution.
- Weigh out accurately about this amount of oxalic acid and transfer to a beaker. Dissolve with about 150ml of distilled water.
- Transfer the solution to a 250ml volumetric flask and dilute to 250ml.
- Calculate the concentration and transfer to a labeled bottle.
- Fill a burette with the KmnO4 solution to be standardized.
- Pipette 20ml of standard oxalic acid solution into a flask and add 20ml of 2M sulphuric acid.
- Warm the flask to about 80℃ and titrate the permanganate solution against the oxalic acid. Ass the permanganate solution slowly of MnO2 will be formed. The end point is reached when the addition of one drop of permanganate produces a permanent pink colour.
- Repeat the titration in the usual way
- Pipette 20ml of the iron (II) sulphate solution into a conical flask and about 10ml of dilute sulphuric acid and titrate with standardized KMnO4 solution.
- Repeat the titration in the usual way.
