Nails rusting science project

A. Sorry, Alexis, but this is just a public forum, not a homework hotline, so there's no way you'll get real help in time. But maybe your project title could be "Serendipity Rules!" or "Serendipity: Fail!"

There is a school of thought that says serendipity is an essential part of progress in science (another school of thought says that there is no such thing; that what appears to be serendipity is actually a prepared mind making careful observations).

You threw nails into four liquids with no particular forethought or logic, so here we are. Is there anything you can learn or postulate by looking very carefully at these 4 sets of nails and thinking real hard? Best of luck!

Regards,

A. Hi, Diana.

The best nails would be hardened masonry nails if available, but lacking that, common nails will be okay (try to avoid "roofing" nails as they are galvanized to deter rust).

I think you should ask your teacher exactly what s/he means by "rust" so there is no conflict later. Then you can graph the four liquids against a scale of least rust to most rust.

Regards,

A. The nails that Ted is referring to are rectangular nails and are frequently called "cut nails". Whatever nail you use, you need to sand it till it is a shiny steel color. The cut nails have a heavy oxide coating and most other nails have a galvanized or plated zinc coating. You need to get rid of the oxide and the zinc.
Next, you need to have about half of the nail out of the liquid as iron needs oxygen to rust. There is some dissolved oxygen in most water, but it is not uniform.
Finally, all 4 samples need to be at the same temperature.

Milk is a poor choice as it will sour in a day or two and your test needs to be a couple of weeks long. Also, it is no longer truly "milk".

---

Very well thought out reply, Jim.

Thanks.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
May 11, 2011

A. Hi, Destiny.

Plain steel nails would be best. Either masonry nails or "bright finish" nails. They will rust faster if you use wear gloves and use sandpaper to rub away any finish on them, but it will be necessary to sand the samples equally or you'll corrupt your comparative test.

Regards,

A. YOU SHOULD USE IRON NAILS AND YES THE WATER WILL RUST FASTER AND MORE THAN ANY OTHER SUBSTANCE

A. Hi. Your first answer is on these pages if you read slowly and pay close attention: vinegar is an acid and acids dissolve rust, so you don't see any in the liquid. But above the liquid level, there were splashes of the acid, acid fumes, perhaps the liquid climbing the nail a bit by capillary action. In short there was acid there that dissolved iron and/or rust, and now that the wetness has evaporated, the iron can't stay dissolved, but appears there.

Regarding the second question, are you sure the rod was iron? I would have expected some rust in 10 days.

Regards,

A. Hi Stephanie.

No one should try to answer that until you do the experiment, or you will just be reinforcing exactly how NOT to conduct science, because you will surely jury rig your observations to match your expectations, consciously or unconsciously. Just do the test and honestly record your observations. If and when you see a pattern, you recheck a couple of times to make sure it is not a random variation, and nothing else is causing the difference. Only then do you start looking for causality.

I could probably tell you that I'd expect little if any difference in rust removal, but that too might influence your observations.

Regards,

A. Hi Andrew.

I'm not quite following your description; remember, we readers weren't looking over your shoulder as you did the experiment :-).

The nails rust, not the coatings, of course. Crude oil isn't quite a "coating" in the same sense as rust-guard paint or galvanizing: are you saying that you dipped a plain steel nail into crude oil and used the dripping nail? I also want to make sure what you mean by "a control" in this context. Are you saying that your control was a plain steel nail with no coating?

Next, I don't know what you did for the exposure: immersed the nails in plain water, salt water, or acid -- or just left them in the air. Finally, I don't know what you mean by "exhibiting the most rust": looked brownest, had the most weight gain, the most weight loss, or what?

It is not uncommon for galvanized articles to get a brown stain, because the surface has a small amount of iron on it due to the way a bit of iron diffuses into the coating while it is molten.

In the end, you need to state your original hypothesis, explain the experimental setup you used to try to prove it, note the results that you got, state how the results supported or contradicted your hypothesis, and explain (to the degree that you can) why things happened the way they did. One other thing you need to do, and it's especially important in very small scale and limited experiments like this, is to explain the limitations of your experiment. Sometimes those limitations are the explanation for most or everything you saw; but if your report can then suggest a better way to do the experiment next time, to limit the influence of extraneous issues, you can count your experiment a success even if it didn't quite prove or disprove the hypothesis.

Regards,

A. Hi Amaya. Probably laundry bleach ⇦ bleach/sodium hypochlorite in bulk on eBay or Amazon [affil links] . Ask a parent to help you test it.

Nice to get a question from my home town! I grew up in E.O. and lived there until 23 years old when I got married: North Maple Ave., then Rutledge Ave.

Regards,

A. Hi Clarine. I spent a week in your beautiful and interesting little country 25 years ago and always like to hear from Singaporeans.

Please pick "bright finished" nails or "masonry" nails, and preferably apply a little sandpaper to them first. And be careful to avoid hot dip galvanized roofing nails (which were carefully corrosion-proofed) ... and then I'm confident that they will significantly rust in less than two weeks.

As for the mass, what happens is some of the iron (steel) in the nail reacts with oxygen in the air and forms iron oxides (rust). So, in one way, the mass actually increases since the mass of the iron oxide that is formed from the iron in the nail plus the oxygen in the air will be greater than the mass of the iron only. But in another way, the rust is usually poorly adherent and brushes off; after the rust falls off or is brushed off, the mass of the iron left in the nail is less than you started with. Good luck.

Regards,

A. Hi Trystan. "Scientific Education".

Regards,

A. Hi Zach. I would suggest that you get some sandpaper and try to sand the nails so whatever coating may be on them is removed. A problem with your drink selections is that you don't really know what is in "soda" or "sports drink" as they are secret formulas, so you project would be a bit stuck from the beginning because how will you know if their effects or lack of effects is due to secret ingredients?

I would keep the coffee, orange juice, and water, but would add vinegar as a fourth liquid. And I would ask the teacher for pH paper, which is used to measure acid. Most importantly, make a "lab book"

Regards,

A. Hi Ally.

Salt water is more conductive (carries electricity better) than plain water or sugar water because the salt, NaCl, dissolves into water as Na⁺ and Cl^-, and these ions can carry electrical charge from point to point helping electrochemical reactions like rusting to take place. In my own experiment on this, however, the nails did not rust faster in salt water, so I would be cautious against the possibility of "junk science" (knowing what you what the answer to be, then discounting contrary results as quirks, and giving disproportionate weight to findings which support your expectations.

I know nothing of teaching, or the mental maturity and interests of 5th graders, but since I suggest the following to students when they write to us, you can determine whether it should have any applicability to your students: lab books / log books.

In research laboratories, "lab books" have traditionally been kept to aid in patent filings, help make experiments more repeatable, etc. They simply involve starting with a book with bound pages like a composition book or pocket composition book, numbering the pages in ink, and only writing in ink. Nothing is ever crossed out to the point of illegibility. Rather a line is struck through it, but it's left legible. Then the student (or the teacher) writes everything they do, and everything they observe, in the book along with the date and time. Accurately maintaining experimental results is probably the most essential step in science, so maybe 5th grade isn't too early :-)

Thanks for being a teacher -- a job that would fry me the first day.

Regards,

A. Hi Christine. First let's discuss what is happening and why. Any acid, including jackfruit extract or Coke, will dissolve rust. Acid is routinely used in industry for that purpose. But the acid which adheres to the surface, as it dries, can no longer keep the rust dissolved, and it re-forms. Further, with the remnants of acid on the nail there, they will dissolve the steel of the nail, and the oxygen in the air will combine with that dissolved steel to form more rust. This propensity for rust to form again after removal with acid is called 'flash rusting'.

The way to 'fix' it is to dip the de-rusted nail into a solution of baking soda for several seconds to neutralize the acid, rinse it, dry it, and wipe it with machine oil. The nails should not rust again for at least several days. If you don't have baking soda, at least rinse the nail well, dry it, and wipe it with oil. If the teacher won't let you use motor oil or machine oil, but wants use to only use edible materials for safety, then olive oil or mineral oil will be better than nothing. Good luck!

Regards,

A. Hi Harold. Ideally he would want to use bare steel bolts because they rust the fastest. But because they rust the fastest and are therefore much less useful than bolts with good protective coatings, they're not very available.

So I'd suggest shiny zinc plated bolts, and try to remove at least some of the plating with sandpaper. If you have a low power battery operated drill you can chuck the bolts in it for sandpapering. But please read this thread about "lab books" because I think a good lab book is more important both to your son's grade and to his learning than the specific results from his testing. Good luck.

Regards,

A. Hi again. A week sounds good to me.

Regards,

A. Hi Jorge. Aluminum nails will never rust, and stainless steels will rust only a little bit after a long time. Of the nails made of steel/iron, I would expect roofing nails with their heavy, drippy, hot-dip galvanized coating to last the longest. Whether "bright finished" nails or hardened "masonry nails" will rust fastest, I'm not sure. So I'd suggest trying those two types in your experiment if you are looking for quick rusting.

(Good luck to your gang, but please be aware that your IP address is included in every e-mail you send, so the postings you sent with fictitious names were received as well, and we know you sent them).

Regards,