Rusting To know what conditions are needed for iron to rust, and how this can be prevented Wednesday, August 05, 2015
Chemical Reactions Some chemical reactions can be useful, whilst others can be less useful Look at the following, and decide if they are useful or less useful…
Rusting Rusting is a less useful chemical reaction Rusting occurs when iron or steel is in contact with both water and oxygen Rusting is a chemical reaction, which produced the reddish-brown iron oxide
Rust Problems If rusting requires both water and oxygen to occur why do you think rusting can be a problem? What measures can be taken to prevent rusting?
Experiment Your task is to carry out an experiment to identify the best way to prevent rusting… Collect the following: - 5 test tubes 1 beaker Cotton wall 1 painted iron nail 4 normal nails 6 labels
Experiment 1. Place the painted nail in a test tube and totally cover with water – label this painted nail + water 2. Put a plain nail in a test tube and ½ cover this with water – label this control 3. Cover a plain nail in Vaseline (using a paper towel) and totally cover with water – label this greased nail 4. Add some calcium chloride crystals in a test tube, and add a little cotton wool in the top of the test tube, pushing it down with a spatula so that it is just above the crystals. Add a plain nail on top of the cotton wool, and place some more cotton wool in the top of the test tube – label this calcium chloride 5. Put a plain nail in a test tube and totally cover this with boiled water. Add a little oil on top of the water, and bung the test tube – label this oil 6. Label your test tube with your group names
Prediction Write a prediction for which nail you think will rust the most / least… Remember we had: - Painted nail + water Plain nail + ½ water + ½ air Plain nail + Vaseline Plain nail + no water (calcium chloride) Plain nail + boiled water (no oxygen in water) We should find the pained nail; plain nail + Vaseline; plain nail + no water; and plain nail + boiled water rust far less than the control (plain nail + ½ water + ½ air) as we are removing one of the substances needed for rusting (both water + oxygen)
Rusting Rusting is a real problem for iron and steel which is in contact with both water and oxygen – i.e. boats / vehicles and other objects which are subjected to the elements However, we can prevent rusting by removing one of the requirements – i.e. remove the water from contacting the iron (by painting it)