What rusts iron quicker?

The aim of the investigation is to find out what speeds up or slows down the effects of rusting in iron. To do this I will place Iron in different solutions restricting certain things getting at it to see what it is that rusts the iron the quickest and what prevents it. To do this I will be testing nails with: no water but air, water and air, salt water and air and a magnesium covered nail in water and air.


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To ensure that this experiment is performed safely everyone doing the experiment should be standing up to avoid spillages. All loose items of clothing and bags should be out of the way to prevent people getting things caught or falling over things. Safety goggles must be worn at all times to ensure that nothing gets into the eye and creates damage to the eye.


Equipment list:


* Test tube (x5)

* Nail (x5)

* Magnesium

* Water

* Salt

* 2 bungs

* Drying agent

* Oil

* Kettle

* Test tube rack


i. Boil the kettle (for the one that uses boiling water)

ii. Put one test tube into each of the sections in the test tube rack.

iii. Drop one nail into each of the test tubes (remembering that one of them must be wrapped in magnesium first.

iv. Add the liquid/powder into the correct test tubes making sure that they are done at the same time using the same amount of liquid/powder (80mm?).

v. Place the bungs into the ones that need it (the one containing boiled water and the one with the drying agent)

vi. Put them in a safe place for 4 days.

The end result of the experiment is the amount of rust present on the iron when the experiment is over and what colour the rust is. The amount of experiments taking place allows for a good look at what things prevent rusting and what things help speed up rusting.

Fair test

To make it a fair test the nail must remain the same size and for there to be the same amount of nails in each test tube. The amount of solution/powder in each test tube must be equal also to enable the test to be fair. They must all have the solutions added at the same time and be left for the same amount of time to enable the results to be fair and for there to be no specific variables (like room temperature etc.) for each test tube.

What will be changed is what the solution/powder is that is added in with the nail and what the nail may be surrounded in. These will be changed so that it can be established what speeds up or slows down rusting.


The results, to ensure accuracy, to help with averages and to dispel any incorrect results, will be repeated. It will be carried out a total of 3 times especially those that are odd and do not fit in with the others.

To make it accurate the liquid is being measured in mm? because it is a more accurate measurement.


I predict that the ones that will rust will be the control and the one with salt water, air and water. The one that has the nail surrounded with magnesium will react in a different way. Magnesium is higher in the reactivity series than iron, and thus is more reactive. Due to this the magnesium will take on the reactions of the iron, and rust, (in sacrificial protection) leaving the iron free from rust.

The control will rust because rust is a compound created from the reaction of iron with oxygen and water. The iron needs both oxygen and water to rust, which is why the one with the drying agent (and no water) and the one with the boiled water (and no oxygen) will not rust.

The one with the salt should react the most. This is due to the fact that salt is a catalyst to the effects of rusting and will produce more rust at a faster speed. The reason for this quicker reaction is that salt dissolved in water is a good conductor of electricity. In order for the iron to rust, electrons must flow from the iron atoms to the oxygen from the air. Iron plus oxygen makes iron oxide. Iron oxide is rust. When the iron producing iron oxide comes into contact with the conductive salt solution, rusting becomes a quicker process.



How much rust?

What colour is the nail?

Other observations

Magnesium + nail + air + water

Medium amount on magnesium.


The magnesium is black/orange

Nail did not rust the magnesium did.

Boiled water + nail + oil



Did not rust

Control (nail, water, air)

Medium amount of rust.

Dark red/orange

Rusted in most places.

Drying agent + air + nail



Did not rust

Salt water + nail + air

Large amount

Black/dark red/orange

Rusted completely. No shiny parts.


The practical experiment went according to plan to produce sensible, clear results that went well with the prediction. There were no results that did not fit.

If I re-did the experiment I would ensure that the water would boil more in the ‘no air’ experiment to ensure that absolutely no air got in and it would produce no rust at all as there was a small amount.

The one that worked the best was the one containing drying agent. This presented no rust and had the reaction (ie. None) that was expected and was the easiest to tell that it had worked.


I conclude that without water or oxygen iron will not rust. Also if you place a more reactive metal around the iron nail it will become sacrificial protection and the more reactive metal will take on the rust leaving the iron without rust. Salt, as predicted, worked as a catalyst to speed up the reaction of rusting onto the iron.

Therefore to prevent rusting you can coat it in a more reactive metal so that the more reactive metal will take on the rust or you can take away all moisture or oxygen. The things cause rusting are water and oxygen but when salt is added to the mixture it speeds up