I need Info

[Linda71f]

My 10 yr old has been handed a topic of " Which Juice will clean a penny the best? " While we know it will be the once with the most acicity, we need to know how to get started and how to find specific info on this topic. ANy suggestions ?

[matthewmulanax]

Linda71F:

One way to look at this assignment is to think about what juices are the most acidic or sour. Starting with citrus - orange (sort of), lemon (definitely), grapefruit (really).

Next look at vinegar, pomegranate, carrot and other vegetables.

You should use water as the control or standard.

Do not hesitate to ask any other questions.

Matt Mulanax

[Linda71f]

Thanks Matt !

Is there a specific place we can get research material?
Also, how do we show as a variable the difference in how dirty each penny is before we test it ?

[matthewmulanax]

Linda71f:

You can try searching Google using words such as cleaning coins, cleaning pennies, acid solutions effect on coins - key words related to your topic of interest.

You can document the change in "color" of each individual coil with a digital photograph of before and after treatment. If you have access to a photographic light meter you can get a relative reflectence valu before and after treatment also.

Your variables will be the different treatment solutions.

For this project the variables are the individual solution used to treat the coins.

If you have any more questions please ask.

Matt Mulanax

[donnahardy2]

Hi Mom,

Here are a couple of websites that will give you more information about the chemistry of cleaning copper pennies. The demonstration on the taco sauce is quite good and will give you an idea of what will happen with your experiment.

http://chemistry.about.com/cs/demonstra ... 22204a.htm
http://www.cruftbox.com/cruft/docs/cleaningcopper.html

Copper pennies turn dull over time because the copper metal is oxidized to copper II oxide (CuO). The chemical reaction is:

2Cu + O2 goes to 2CuO (copper is oxidized from Cu to Cu II)

A solution containing salt (NaCl) and acid will dissolve the copper oxide from the surface of the penny, leaving the shiny, unoxidized copper layer showing through. The oxidized copper will be in the acid solution used to clean the penny.

I've never worked with a 10 year old that was interested in, or could understand the chemistry involved with this experiment. I would suggest trying out different combinations of salt and acid and just observing the results. You can point out other examples of oxidation, such as a rusty nail, rancid oil, burning gasoline, or metabolizing food into energy. You can try different types of acid. Weak acids are found in Vitamin C tablets (ascorbic acid) vinegar (acetic acid) and oranges or lemons (citric acid); A stronger acid is found in Lime Away (phosphoric acid).

I would recommend encouraging your son to experiment and try to discover something about the chemistry of the reaction.

Is this enough information, or do you still have questions?

Donna Hardy

[geoffbruton]

One other thought:

One way you may be able to more visually demonstrate the cleaning effect on the coins may be to only partially submerge the coins in the test solution. If you could suspend the coin such that only half was submerged, the cleaning effect could be readily observed on the half that was in the solution versus the half that was not. Does that make sense?

Digital photographs could then be added to the final display and would aid the viewer in how you reached your conclusions.

Good luck with the experiment, and please keep us informed on your results.

Best wishes,
Geoff.

[Linda71f]

Thanks to all that took the time to answer !!! I did find some really good material in a teaching aid science book at the book store today realted to a similar experiment .

Love the idea of partially submerging the pennies !

Wish us luck...thanks again !

Linda

[nicu]

I think those based on Vitamin C but i'm not that sure.