I don't know if $\ce{C}$ or $\ce{CuO}$ react with $\ce{H2SO4}$. Some sources say that: $$\ce{C + H2SO4 -> CO2 ^ + 2SO2 ^ + 2 H2O}$$ (It seems to be similar to $\ce{Cu}$ reactions with $\ce{H2SO4}$). Is the reaction possible? If the answer is yes, in what conditions does the reaction take place?

And I was pretty sure that $\ce{CuO + H2SO4 -> CuSO4 v + H2O}$

But my chemistry book says that none of the reactions is possible. I'm little bit confused, some help would be apreciated.


Carbon reacts with sulfuric acid to produce carbon dioxide and sulfur dioxide gas along with water. Sulfuric acid should be a concentrated, heated solution.

$$\ce{C + 2H2SO4 ->[\Delta] CO2 + 2SO2 + 2H2O}$$

More insight about this reaction can be found here.

Copper(II) oxide, a black solid, and dilute sulfuric acid react to produce copper(II) sulfate, giving a characteristic blue colour to the solution. From this solution, blue copper(II) sulfate pentahydrate crystals may be obtained if desired.

$$\ce{CuO + H2SO4⟶CuSO4↓+H2O}$$

It is a general "insoluble metal oxide is reacted with a dilute acid to form a soluble salt" type of reaction. It is a standard class experiment.

More insight about this reaction can be found here.


1) $\ce{H2SO4}$ can react with pure graphite powder/ash at elevated temperatures. It is a Redox-reaction between $\ce{C}$ reducing $\ce{S}$ while being oxidized. Typically adding hydrogen peroxide to $\ce{H2SO4}$is required to oxidize carbon which actually is the result of a new acid peroxysulfuric acid $\ce{H2SO5}$.

2) $\ce{CuO}$ can be dissolved with $\ce{H2SO4}$. You can as find some "proof" here, note that the product turns blueish in the end, which is the color of $\ce{CuSO4}$. On the German wikipedia entry the formula is even mentioned in the synthesis section.

Both reactions work only with concentrated acid and with heat because $\ce{CuO}$ and $\ce{C}$ are thermodynamically stable and a certain temperature is needed before the reactions become exergonic.

  • 2
    $\begingroup$ My lab coat is made of carbon ??? $\endgroup$ – NotEvans. Dec 28 '15 at 19:12
  • $\begingroup$ Partly, if yours is also made from cotton. $\endgroup$ – BeschBesch Dec 28 '15 at 19:17
  • $\begingroup$ @BeschBesch thanks! What about $\ce{CuO + AgNO3}$ is it possible? If not, please explain. $\endgroup$ – scummy Dec 28 '15 at 19:57
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    $\begingroup$ @BeschBesch Don't confuse people. Lab coats are not even partially made of elementary carbon (and in any case, carbon is not why they are vulnerable to $\ce{H2SO4}$), dissolving $\ce{CuO}$ requires neither heat nor concentrated acid, and $\ce{CuSO4}$ is not blue (though its hydrate is; however, with concentrated acid you won't get the hydrate). $\endgroup$ – Ivan Neretin Dec 28 '15 at 20:21

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