Metal finishing Q&As since 1989

-----

Which soda will rust a nail fastest?

My 9 year old (3rd grade) has chosen which soda (Coke, Pepsi, Dr. Pepper) will rust a nail fastest for her science project. Keep in mind this is not remove rust. We watched this for 6 weeks (The nail in the bottle of Coke rusted first) but her teacher wants research from the internet. I can't find it anywhere

Pat Gass
student - Minneola, Florida
2007

---

2007

And as the parent, what do you think about the teacher wanting "research" from the internet as opposed to the library, Pat? How will you have the tiniest confidence that the information is reliable? It won't be.

Unfortunately I doubt that you will find any reliable research on this subject either in the library or on the internet because their is no extensible science to be learned from it. Coke can change their secret formula at any time, as can Pepsi. And even if the results were documented and repeatable, you would be no closer to learning anything because you don't know what ingredients are in either.

I think the point of the project is not actually to determine which secret formula soda rusts a nail faster, because there is no actual use for such information. I think the point is for your 3rd-grader to begin learning how to conduct such projects and experiments. The way to do it is to choose a hypothesis: "I think Coke will rust a nail faster than Pepsi or Dr. Pepper" and then to design an experiment to support the hypothesis or refute it. And then to come to a conclusion (however tentative) and write your results. Then, of course, you can compare your conclusion to the conclusion that others reach.

Personally I think you should buy a small bound notebook, number the pages and write on page 1, "My hypothesis is: ... ". Then on page 2, write your design for the experiment -- what you will do and why you think it will support or refute the hypothesis. Then you start writing the results, and here is why the pages are numbered: because you never cross out a result and never rip out a page. Then with all the results in hand, if you think any were wrong, you explain why. After you have explained away the results you feel were erroneous, you write a conclusion based on the other results. Now, if you can find any supporting or refuting research, you include that.

If your 3rd-grader does that I think s/he will get an A+

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