The authoritative public forum
  for Metal Finishing since 1989
-----

Protocol for a corrosion experiment

Hi, I'm 15 years old , me and my partner are doing this project for science fair. We want to find out which of the seven metals will oxidate (rust) the fastest from steel, iron,copper, aluminim, brass, zinc and magnesium? We are going to use 3 samples of each metal, water, salt, bowls, and a triple beam balance. First, we are going to weigh the metals on a triple beam balance to see if the mass of the metals affect the rusting. Secondly,we will put one set of all the metals into a bowl. We will spray water with salt three times a day.Thirdly, we will put another set of metals in different room temperatures. We will use the attic, where is very humid. The final set of metal will be put outside on the porch to see if will rust fast out side or inside or with water and salt. We want to know if you could give us some advices to see if we are doing ir right or what's needed or what's wrong. We appreciated if you could help us. Thanks tou for your time. please help us. Thank You

ERIKA
Student - Bridgeport, Connecticut, United States
2005

---

2005

Hi Erika,

For a l5 year old, you sound very erudite.

Well, I ain't ... and what in the hell is a triple beam balance?

Firstly, I'd go and have a gander at the galvanic series, if that's the right word ... this, as you probably already know, shows the nobleness of metals ... starting with, I believe, Platinum and then zeroing down to easily corrodable materials like magnesium and zinc.

Whether you put your test samples inside or outdoors has little significance ... temperature increases oxidation, doesn't it? Humidity helps, too.

For fun, immerse one sample in some rye or gin and see what happens,,,, and then you could drink the residue and make a learned comment about preservation, perhaps.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

---

First, if you are using the typical Ohaus triple beam found in schools, its precision may not be fine enough. You might need to use an analytical balance.

Second, the amount of gross corrosion would be more related to surface area rather that original mass (in your experiment, you are looking at environmental exposure).

Finally, how are you going to measure the amount of corrosion? With your setup, you could look at % surface area affected or mass of corrosion (you have to carefully remove the corrosion via chemical means and then re-weigh the specimen). For the mass change method, you REALLY need an analytical balance.

Good Luck!

James Totter, CEF
- Tallahassee, Florida
2005

---

You said that we can remove the corrosion via chemical means.. How do you do that? Can you please offer methods?

Thanks.

Claire Cororaton
- Falls Church, Virginia, USA
2005

---

Hello, I'm a high school student and I'm currently planning my Chemistry corrosion experiment. It involves two aspects:
a) a factor that causes or promotes the corrosion of iron
b) a prevention method of the corrosion of iron.

For aspect a, I'm going to investigate how the salinity of water increases the rate of corrosion of iron. For this, I'll have the same amount of water, same iron nail, and different amounts of salt in each test tube. I'm pretty confident on how I'm going to go about it. As for measuring corrosion, I've researched that I can easily weigh the nail before and after. I'm going to scrub off the excess rust at the end of the experiment and determine the weight loss - or should I keep all the rust on the nail and determine how much more it weighs? That's all I'm not so sure about

As for aspect b, I'm going to investigate the effect of different metals (varying in reactivity levels - some less reactive and others more reactive than iron) when in contact with the iron nail. My hypothesis is that the more
reactive metals are more efficient in protecting the iron from corroding. So, my experimental design will involve iron nails in each test tube and each will have metal around it, including copper, tin, lead, zinc, aluminum, magnesium and also a galvanized nail. The only aspect I'm frustrated about is how I'm going to obtain quantitative data. I know the easiest and simplest way is by using the weighing method. However, some of these metals will obviously react with the iron nail and water to produce harmful chemicals, so I can't simply take each iron nail with the metal out and weigh it on a balance. What do you think I should do?

Raisa T [last name deleted for privacy by Editor]
- Brisbane, Queenslands, Australia
February 13, 2011

---

Hi, Raisa

Because some of the corrosion products will have sloughed off, weighing the nail with the rust on it won't work. Your idea of rubbing the rust off before weighing is a better one.

For aluminum, magnesium, and zinc you can just weigh the steel nail, as these protect the nail sacrificially. I don't think the other metals will deposit onto the steel nail or otherwise interfere with your experiment, but will themselves react with the salt water and slough off. Note that the steel nail must be in contact with these other metals for any galvanic protection or acceleration of corrosion to occur.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 14, 2011