The presence of a powder of this element facilitates the formation of a diaryl ether in the Ullmann condensation.
This element and chlorine are the namesakes of a four-step thermodynamic cycle that produces hydrogen gas and oxygen from the splitting of water. The presence of a powder of this element facilitates the formation of a diaryl ether in the Ullmann condensation. This element's chloride acts as a co-catalyst to prevent the formation of a precipitate in the Wacker process. A (*) sulfate of this element is combined with Rochelle salt and serves as the oxidizing agent in one test to distinguish between aldehydes and ketones. A precipitate of this element's insoluble red oxide indicates the presence of reducing sugars in Benedict's test, and this metal produces a blue-green color in a flame test. For 10 points, name this metal found in Fehling's reagent, and in alloys such as brass and bronze. 
This element and chlorine are the namesakes of a four-step thermodynamic cycle that produces hydrogen gas and oxygen from the splitting of water.
copper