Why did this happen?

Question

For my science fair project I was rusting non-galvanised steel nails in different concentrations of salt water solutions. The nail with the least salt in the water rusted faster than some of the other nails. Why did this happen?

Answer 1

salt contains preservatives and is used to preserve matter. The more salt, the slower the reactions, thus the thing is preserved.

Answer 2

I figure the hypothesis of your project was to show that non-galvanized steel nails would rust faster in solutions containing higher concentrations of salt due to salt being an electrolyte and creating a solution that is able to conduct electricity better thereby increasing the rate at which the steel would rust at higher concentrations of salt in the water. So, it would seem unusual that the water with less salt would cause the nail to rust faster than some of the other nails. The only factor that you cannot control is the quality of the nails or how they were manufactured. I would surmise that there is the possibility that the nail already had rust on it that was not visible to your eye prior to the experiment starting.

Answer 3

There are several possibilities.

1. Nails are like meat in that rust is like bacterial rot. I think that's what answerers 1 & 2 are saying.
2. Whatever chemistry is involved in rusting, salt gets in the way.
2a. Salt can get in the way by attaching itself to the nails before oxygen can do it, so oxygen fails to produce rust.
2b. Salt removes or combines with the stuff in water that causes rust, which is oxygen. Is there such a thing as salt oxide?
2c. Salt interferes with the movement of oxygen toward the nails, so the oxygen stays put and it can't oxidize the nails.
2d. Salt causes the oxygen in the water to escape from the water (bubble out or vaporize out), or it causes something else unseen in the water to combine with the oxygen (acting like a catalyst), and then the oxygen doesn't produce rust because it's bound up in some unseen dissolved chemical compound.
2e. Salt sucks something out of the nails so that the nails don't attract oxygen anymore.

Now all you have to do is test each hypothesis.

Answer 4

Ignore previous answers. The reason is that rust is ferrous oxide, a combination of the elements iron and oxygen (FeO). When you add salt (Sodium Chloride, NaCl) you change the composition of the water and the oxidisation process is affected causing a slowing of the process. Water, of course, is H2O. The rust is caused by the release of the oxygen that combines with the iron. Addition of salt affects the process. The water then becomes a salt solution, in other words, a different substance.

Answer 5

salt preserves things