kat's "a penny for your thoughts"

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  • 1.

2. Which solution (vinegar, lemon juice, Salt water, or baking soda) will clean tarnished pennies the best? 3.

  • Tarnish Happens when metal combines with oxygen. The air has to be damp
  • Acids can dissolve rust (tarnish) well
  • On the ph scale, a ph of 7 is neutral, higher than 7 is basic, and lower than 7 is acidic.
  • Lemon Juice has a ph of 2.2
  • Vinegar has a ph of 2.8
  • Baking soda has a ph of 8.4
  • Saltwater has a ph of 8
  • Oxidation, which causes tarnish, is a chemical reaction.
  • Oxidation happens with reduction, which is when something gains electrons.
  • In oxidation, a substance looses electrons
  • Ph (on the ph scale) stands for the power of H, or hydrogen
  • The lower something is on the ph scale, the higher its acidity
  • Rust can weaken a penny or other metal material.
  • The green patches on pennies are called copper oxide. It is caused by oxidation
  • When acid reacts with tarnish, it makes a penny shiny.


  • Busch, Marianna A. "Oxidation."World Book Student.World Book, 2011. Web. 30 Mar. 2011. http://www.worldbookonline.com/student/article?id=ar409320
  • Author, Unknown. "ph Scale Comparisons."Bioworld Products . N.p., n.d. Web. 11 Mar. 1930. < http://www.bioworldusa.com/household/ph-scale-comparisons>.
  • Hapeman, Cathleen J. "Reduction."World Book Student.World Book, 2011. Web. 30 Mar. 2011. http://www.worldbookonline.com/student/article?id=ar462660
  • "Tarnish."World Book Student.World Book, 2011. Web. 30 Mar. 2011 http://www.worldbookonline.com/student/article?id=ar547480&st=tarnish.
  • Ophardt, Charles. "pH Scale."Elmhurst College: Elmhurst, Illinois . Virtual chembook, n.d. Web. 30 Mar. 2011.

5. If we leave 4 tarnished pennies in different solutions to clean, then lemon juice will clean the best because the tarnish on pennies is caused by oxidation. Tarnish can be cleaned well by acids. To find out how acidic something is, you use the ph scale. The lower something is on the scale, the more acidic it is. Lemon juice has a ph of 2.2. That is the lowest of our solutions, so it will clean the best. 6.

  • Heinz distilled white vinegar, 300ml
  • Arm & Hammer pure baking soda, 22.2 ml
  • Pompeii brand lemon juice, 300ml
  • Morton Salt, 22.2 ml
  • 4 clear glass cups
  • Bounty paper towels
  • 22 Tarnished Pennies
  • Stopwatch
  • Pyrex brand metric and customary measuring cup
  • Kitchen aid brand customary and metric measuring set
  • Spoon
  • Paper
  • Permanent marker
  • Penny ranking chart


  • Create a scale of pennies 1-10 ( one being the shiniest) so I can measure before and after.


  • 2. Gather materials


  • 3. Set out 4 clear cups


  • 4. Fill cup 1 with 100ml of vinegar, fill cup 2 with 100ml of lemon juice, fill cup 3 with 100ml baking soda and water, and fill cup 4 with 100ml of salt water


  • 5.Rate all pennies of the sale of 1-10 and record their numbers


  • 6. place 1 penny in each cup


  • 7. After 5 minutes measured with a stopwatch, remove the pennies with a spoon. Dry with a paper towel.


  • 8. Rate all 4 pennies again according to the penny scale


  • 9. Repeat steps 3-7with different pennies and clean cups 3 times


  • Controlled variable:
  • The same scale for the pennies
  • What we are cleaning
  • The amount of solution
  • The time the pennies sit in solution.
  • Same containers for pennies
  • Independent Variable:
  • Each penny will be cleaned by a different solution
  • Dependent variable:
  • The Brightness of the penny will be different based on the solution

17. 18. 19. 20. 21. 22. In our test, lemon juice cleaned the best. It won by 3 points. Vinegar came in second by 5 points. Baking soda came in third by .50 of a point. Salt water came in last, with a score of 3.5 total cleansing. Our results were very varied, like baking soda. In trial one the score was one, in trial two the score was 0, and in trial 3, the score was 3. Although the scores were varied, lemon juice stayed consistently good. 23. Our hypothesis was correct. Lemon juice did clean the best. This is because it had the highest acidity.We think that the experiment was fairly successful, even though our results were varied. Next time we do this experiment,we will try to make sure the pennies are equally tarnished. Some of the tarnish on pennies were unequal.Some tarnish may even have been different kinds. We are curious to know if it was. We enjoyed this experiment because we learned a lot about chemical reactions and oxidation.