While heating copper in the final step, the bright copper color changes to dull brown. will percent recovery be too high, too low, or unaffected? explain your answer

Copper is an element in the periodic table with the chemical symbol Cu and atomic number which is equal to 29. This is a metallic element that is soft, ductile, and malleable. Also, this has very high electrical and thermal conductivity. 

This metal, when freshly exposed is a reddish-orange color. The situation given above, it is described that copper has already reacted with oxygen, as described by the change of color. This means that the percent recovery of the metal will be less since portion of it has already reacted.