D. Crowley, 2008

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)