For this I/GCSE Chemistry blog post, we will be looking into the features and reactions that comes from Iron, as well as the contribution of different types of substances in the atmosphere.
Iron
Iron corrodes easily , it happens when iron is in contact with both oxygen and water= oxidation reaction. ( as the iron gains water ). Water becomes loosely bonded to the iron oxide forming hydrated iron oxide =rust.
Iron + oxygen + water - hydrated iron oxide.
Rust is a soft solid that flakes off to leave more iron available to rust.
Prevent rust:
Barrier method: painting / coating with paint (big structures) , oiling/ greasing (moving parts involved.
Sacrificial method: placing a more reactive metal with iron, the water and oxygen will then bond more tightly with the sacrificial metal than with the iron.
Galvinashing: Zinc is often used as the sacrificial method as its more reactive and will be oxidised instead. A coating of zinc can be sprayed onto the object.
Or big blocks can be bolted to the iron - can be used on ships hulls or underground pipes.
Oxygen in the Atmosphere
Composition of the atmosphere: 21% oxygen, 71% nitrogen, 1% argon and 0,04% CO2.
Investigating the proportion of oxygen in the atmosphere:
Copper:
- When its heated copper reacts with oxygen in the air to make copper oxide - using up the oxygen.
- If you heat an excess of copper and pass air using two sealed syringes you can use the markers to tell how much oxygen has been used.
2Cu + O2 - 2CuO
Iron or phosphorus:
Iron reacts in the air to form rust.
- Soak iron wool in acetic acid- catalyse the reaction, and push the wool to the test tube, invert the test tube into a beaker.
- Over time the level of water in the test tube will rise as the iron is reacting with the oxygen .
- To work the percentage you have to mark the starting and finishing position of water and work the difference of volume.
You can do a similar experiment with white phosphorus as when it reacts with oxygen it produces phosphorus oxide
That's all for this post!
References:
https://www.google.com/url?sa=i&url=https%3A%2F%2Fscied.ucar.edu%2Flearning-zone%2Fair-quality%2Fwhats-in-the-air&psig=AOvVaw1zH8QnPJ9PdkIy2mFytiak&ust=1627869662778000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCIDsyZvdjvICFQAAAAAdAAAAABAD
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.scienceabc.com%2Fpure-sciences%2Fwhat-are-single-replacement-and-double-replacement-reactions.html&psig=AOvVaw3oiDH78XY4quHioIqDwG2v&ust=1627869628950000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCJCRh6jdjvICFQAAAAAdAAAAABAD