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.
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