No, as part of Science Week, we haven’t been training our pupils to be master criminals, we have been cleaning copper coins! Copper pennies look dull and dirty when the copper mixes with oxygen in the air so we separated the copper from the oxygen around it. We prepared a solution of white vinegar and salt by stirring the salt into the vinegar until the crystals could no longer be seen. Vinegar is an acid that makes the copper separate from the oxygen. Adding salt to the vinegar makes it a stronger solution that works faster. Once the solution was poured over the dull coins we saw an immediate change. Left over night the solution did it’s job and in the morning we had shiny coins again. Once rinsed and dried each of the children were given one and they wrote up the test and draw a diagram. We predicted how long it would take for oxygen to turn the now shiny coins dull again. Some of the coins we rinsed but did not dry and the water, copper and oxygen acted together in a chemical reaction and made the coins green!