Science Buddies: "Ask an Expert"

I am doing a project on if the percent of iron in a metal affects the corrosion rate. I was wondering what method I should use to mesure the corrosion rate? I was going to weigh the metal, but Im not sure if the difference in weight loss will be enough to measure.
Thanks,
Cria

Hi Cria,
Measuring the weight before and after is a common method, but it would require an extremely accurate scale. I'm not sure what your science background is, but if you want to do some more complex calculations, you can check out this website:
http://www.ecochemie.nl/download/content/APPL017.pdf
Good luck!

I was wondering how precise the scale has to be to measure the corrosion rate. I have a scale that measures up to tenths of a gram, will that be enough?
Thanks!

Everything is relative....
If you start with a ton of iron and are trying to detect 1000 parts per million, then you need a scale accurate to 2 pounds.

If you start with 2 pounds of iron then you need a scale accurate to .002 pounds.

If you start with 2 ounces of iron then you need a scale accurate to .002 ounces.

Guestimate how many parts per million you need to detect and multiply by your starting weight to get a guestimate of the scale accuracy needed. I think you will find that scales that can measure more than three significant digits are VERY espensive.

I've also heard of a method of measuring the rate using pH, is this true that you can do this?

Hi Cria!
This link explains about the correlation between pH and corrosion rate. http://www.tpub.com/content/doe/h1015v1 ... v1_117.htm
Hope it helps, good luck with your project!