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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: Chromeo33 on August 29, 2011, 08:51:54 pm

Title: Reaction between copper (II) oxide and sulfuric acid!?
Post by: Chromeo33 on August 29, 2011, 08:51:54 pm
... what do I get?

When I wrote out my equation, I ended up with CuSO4 as a product.

But in my prac, I ended up with some precipitate and I THOUGHT is was the CuSO4! But after asking around, I've heard that CuSO4 is SOLUBLE in water and therefore it cannot be the precipitate I had observed in my prac.

Would anyone be able to finalise/correct a couple things with my deductions?

Any advice/help is much appreciated, thanks peeps :)
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: REBORN on August 29, 2011, 09:18:38 pm
CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l)

No precip?
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: Lasercookie on August 29, 2011, 09:27:54 pm
Unless that CuSO4 is one of those exceptions in the solubility rules, it's possible you didn't stir the solutions well enough or something that is caused a precipitate to form.
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: REBORN on August 29, 2011, 09:29:18 pm
All sulfates are soluble except Ca, Ba, Sr, Ag, Pb
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: b^3 on August 29, 2011, 09:32:04 pm
Maybe some impure samples or cross-contamination? Did everyone get the same thing or just a couple of groups?
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: Chromeo33 on August 29, 2011, 09:37:13 pm
Ah crap..

Nah I didnt bother to ask other groups..


lol ok so I must've did something wrong with my prac I'll just double check that tomorrow, thanks anyways guys!
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: b^3 on August 29, 2011, 09:40:46 pm
Might not be your fault. If you are say using beakers from say a class before you that were 'washed', a little bit of the solution may be left over and result in your precipitate that you observed.
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: |ll|lll| on August 29, 2011, 11:31:36 pm
What colour was the ppt? It could be excess CuO that has not fully reacted.
Also, solubility is dependant on temperature. Thus, CuSO4 could have been more saturated at some temperatures than others. Maybe if you heat the mixture, the ppt might have dissolved
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: Chromeo33 on August 29, 2011, 11:32:04 pm
Lol thanks for the consoling words but knowing me and my prac partner, it was most likely our bad :/
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: Chromeo33 on August 29, 2011, 11:38:13 pm
OMGGG I think me and my prac partner may have used an excess of CuO powder so it SEEMED as if there was precipitation.. Is that 'chemically sound'?

If this IS the case, then what should theoretically be observed by adding CuO(s) to sulfuric acid according to this equation:
CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l) ?


Ahh, so stupid..
Title: Re: Reaction between copper (II) oxide and sulfuric acid!?
Post by: Chromeo33 on August 29, 2011, 11:38:53 pm
Quote from: |ll|lll| on August 29, 2011, 11:31:36 pm
What colour was the ppt? It could be excess CuO that has not fully reacted.
Also, solubility is dependant on temperature. Thus, CuSO4 could have been more saturated at some temperatures than others. Maybe if you heat the mixture, the ppt might have dissolved

Yeah the precipitate was black so it may have been unreacted CuO. So stupid..........