Balanced reaction to Cr given H+ [closed]








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The troublesome nature of this post, is that I was given very little information to work with:


"*The metal chromium (Cr) reacts with an acid, to create Cr^+3 ions, and hydrogen gas.
Show the balanced reaction.*"
(paraphrasing)


Addendum:


* It is highly implied that there is water involved somehow, in a follow-up question, there is mention of water-vapor that "carries the hydrogen gas".


Any ideas? :)


EDIT: I failed to mention that the core problem of this question, is that I am entirely unsure with what I am entirely working with here.


"Cr + H^+" doesn't seem right, surely there's more to it?




The half-equations are : $$\ce{Cr -> Cr^{3+} + 3 e-}$$ $$\ce{2 H+ + 2 e- -> H2}$$ So doubling the first and multiplying the second by $3$ and adding the results gives the final equation : $$\ce{2 Cr + 6 H+ -> 2 Cr^{3+} + 3 H2}$$ Water is not taking part to this reaction, except if your teacher wants you to replace the ion $\ce{H+}$ by $\ce{H3O+}$. In this case, the second half-equation becomes : $$\ce{2 H3O+ + 2 e- -> H2 + 2 H2O}$$ And the final equation becomes : $$\ce{2 Cr + 6 H3O+ -> 2 Cr^{3+} + 3 H2 + 6 H2O}$$ But there is nowhere any water vapor, except if you admit hat the hydrogen gas is a little wet and contains here and there some $\ce{H2O}$ molecules.


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