RogueRose
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Cu + H2SO4 + heat = black precipitate & a Sulfur oxide(s) - where is the CuSO4?
I tried adding small clippings of wire (10gr of 18-20ga & 2-3mm length) to 93% H2SO4 as well as 31% then heated. When heated to boiling the
concentrated turned black pretty quickly and emitted a strong sulfur gas whether it is dioxide or triodixe or both, IDK, but it looks like CuO was
produced very efficiently. The diluted acid acquired a grey tint although remains clear.
I've seen a lot of videos where this reaction creates CuSO4 and know that this works when adding H2O2.
Does the Cu act as a catalyst that breaks down the acid. Wiki states that CuSO4 is made industrially by heating the Cu or Cu oxides in hot
concentrated acid. Was too much heat used maybe, that doesn't allow the formation of the sulfate?
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DraconicAcid
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I suspect you'll get CuSO4 in more dilute acid, or under less-than-boiling conditions.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Amos
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Use dilute acid, closer to 10-20%, and use a wide shallow container so it can take up plenty of oxygen to serve as your oxidizing agent.
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