EXPERIMENTAL INVESTIGATION 20.1 What conditions are necessary for the corrosion of iron?
Equipment Test tube rack Mass balance 3 iron nails Tongs
Calcium chloride 3 test tubes
3 test tube stoppers Kettle
Method 1. Set up the apparatus as shown in Fig. 20.5.
2. Using a mass balance, record the mass of the three iron nails.
Water
Plastic dropper Oil
SAFETY • Wear gloves when handling calcium chloride.
3. Calcium chloride is a substance that removes moisture from the air. Using a tongs, place some calcium chloride at the bottom of test tube A. Add the first iron nail to the test tube and stopper the test tube. Place it in the test tube rack.
4. Use the kettle to boil some water. Boiling the water removes any dissolved oxygen in the water. Pour the cooled boiled water in test tube B. Add the second iron nail to the test tube and, using a plastic dropper, add a layer of oil to the top of the water. This will prevent any oxygen from the air dissolving in the water. Stopper the test tube and place it in the rack.
5. Pour some unboiled water into test tube C. Add the third iron nail to the test tube. Stopper the test tube and place it in the rack.
6. Leave the test tubes for 5 days. Then, take the mass of each nail again and record your results. Test tube stopper
Oil
Iron nail
Calcium chloride
A
Boiled water
BC :Fig. 20.5 To investigate the conditions necessary for the corrosion of iron j Go to page 50 of your Experimental Investigations Log to write up this investigation.