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How To Clean A Penny
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For this experiment, you will not need
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The aim of this experiment is to demonstrate the chemical reaction that takes place when an acid is added to a basic oxide.
Place about 2 tbsp of lemon juice and 1 tsp of salt in a glass. Mix together thoroughly until the salt dissolves.Then drop a dirty old penny into the solution. Swish it around a bit so that the penny is completely covered. Fish it out and see how shiny it is! Good as new.
Why did this happen? When the lemon juice and salt were mixed together, they underwent a chemical reaction that produced a weak hydrochloric acid solution. The penny is made of copper. It is dirty or tarnished because the copper has reacted with oxygen in the air over time and a layer of copper oxide has formed. When the penny is placed in the hydrochloric acid solution, another reaction takes place. The copper oxide reacts with the hydrochloric acid to produce copper chloride and water. This leaves the penny clean and free from any copper oxide build up.
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