The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Does the Temperature of Water Affect the Rate of Oxidation of a Nail?

I am in the 7th grade and I did my science fair project on "Does the Temperature of Water Affect the Rate of Oxidation of a Nail?" The expiration of the experiment was for 2 weeks. I used hot water (98 F), room temperature water, and cold water (35 F). The hot water turned out to rust faster than the cold water. Is this supposed to happen ? If so, why did the nail in hot water rust faster than that of the cold water?

Bob Z.
Student - Albany, New York, U.S.A.
February 17, 2010

---

First of two simultaneous responses --

Absolutely! Get a high school chemistry and look thru the sections on rates of reactions. Typical is the rate doubles for every 20F rise in the temperature. That is not an absolute figure, but it is a commonly accepted one for estimating purposes.

James Watts
- Navarre, Florida
February 18, 2010

---

Second of two simultaneous responses --

Bob,

I don't know your schooling level so it is difficult to know where to pitch the answer.

What you need to do is look up the effects of temperature on reaction rates.

Firstly explain chemically what is happening when an iron nail rusts. What are your starting materials, what are the reaction products?

Then you will need to look up about reaction kinetics, most common school texts will have a section on this. If you look it up you will find a good general rule of thumb (doesn't work exactly or all the time, but is a close enough approximation for your needs).

Armed with these two pieces of information you will be able to answer why the nail in warm water rusts quicker than one in cold water.

Brian Terry
Aerospace - Yeovil, Somerset, UK
February 19, 2010

Also look up the solubility of different gases in water at different temperatures. It may give you an understanding of why the estimate James gave, with the rate doubling for every 20°F, doesn't always work.

Ciaron Murphy
- South Wales, UK
February 22, 2010