Lab Report
Research
To be able to properly conduct this experiment, we researched the procedure thoroughly beforehand. We used multiple websites to see what different methods there were to the experiment, (ex: different ingredients, different quantities) and compared the differences to the other instructions. The instructions that proved to be the most common were the ones we chose to use, as it was more likely that they would be successful. We also watched YouTube videos to see how the results would look in action.
Procedure
To carry out this experiment, we used clean pennies, 115 ml of water, 3g of zinc metal powder, 65 ml of sodium hydroxide, a hotplate and 2 beakers. First, we filled one of our beakers will 115 ml of water, the other was filled with water as well but the amount was not specific. We then added the sodium hydroxide to the water as well as the zinc powder to the 115 ml of water. After stirring it for a bit, we placed the solution on the hot plate and let it heat up until it came to a gentle boil. Once it was boiling, we added in the pennies and let them “cook” for a few minutes until we could see that they had a silver coating. We then removed the pennies using tongs, and dropped them in our other beaker of water so they could cool down.
To turn the pennies gold, after they had been turned silver and cooled down, we placed them on the hot plate. The pennies then quickly changed from silver to a gold colour. Then we dropped the gold penny in cold water, and we had our “gold” and “silver” pennies.
Chemical reaction
The science behind changing the penny’s appearance for the silver pennies was galvanization. The hot sodium hydroxide reacted with the zinc metal to make a soluble sodium zincate which then became a metallic zinc when it touched the copper pennies. This resulted in the pennies being coated in zinc, giving them a silver-like appearance. For the gold pennies, when the copper and zinc came in contact with direct heat, the zinc and copper fused together to form a brass coating which has a golden colour.
Outcome
Our experiment was successful, we were able to achieve both gold and silver coloured pennies.
Magic
This experiment is magical because you are taking something that now has no value in the Canadian monetary system, and giving the impression that it has now transformed into something of higher value (silver and gold). The process of turning the silver penny gold is especially magical looking. The silver penny appears to turn gold all on its own, there is no stirring, boiling, or other liquids involved.
Sources:
Experiment procedure by E. Bekker
http://chemistry.about.com/od/chemistryhowtoguide/a/goldsilverpenny.htm