@Jan - a lot of good stuff gets dissociated in the chat, why not bring it here, by a salt bridge, as it were; lest the half-cells become unbalanced.More
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A non-oxidising acid is an acid in which there is no stronger oxidant than $\ce{H+}$ at $\mathrm{pH}\ 0$.
Or, in a slightly different wording, a non-oxidising acid would be one that cannot dissolve any noble metal at $1~\mathrm{M}$ concentration, but should (in the absence of effects like overpotential) dissolve any non-noble metal at that concentration.
Nitric acid has the strong oxidation agent $\ce{NO3-}$ present, which will reduce to $\ce{NO}$ or $\ce{NO2}$ depending on the concentration. It is able to oxidise noble metals such as silver.
Hydrochloric acid, on the other hand, has no other oxidising agent. The chloride ion is already fully reduced. Therefore, it is not able to oxidise noble metals such as copper.
Some acids are more strongly oxidising if they are concentrated. Sulphuric acid is one. Only in higher concentrations will reduction of sulphate to $\ce{SO2}$ take place and make the acid oxidising. In lower concentrations, only $\ce{H+}$ takes part in oxidations.
A non-oxidising acid is an acid in which there is no stronger oxidant than $\ce{H+}$ at $\mathrm{pH}\ 0$.
Or, in a slightly different wording, a non-oxidising acid would be one that cannot dissolve any noble metal at $1~\mathrm{M}$ concentration, but should (in the absence of effects like overpotential) dissolve any non-noble metal at that concentration.
Nitric acid has the strong oxidation agent $\ce{NO3-}$ present, which will reduce to $\ce{NO}$ or $\ce{NO2}$ depending on the concentration. It is able to oxidise noble metals such as silver.
Hydrochloric acid, on the other hand, has no other oxidising agent. The chloride ion is already fully reduced. Therefore, it is not able to oxidise noble metals such as copper.
Some acids are more strongly oxidising if they are concentrated. Sulphuric acid is one. Only in higher concentrations will reduction of sulphate to $\ce{SO2}$ take place and make the acid oxidising. In lower concentrations, only $\ce{H+}$ takes part in oxidations.
Jan, are there any cases where the oxidising power of the anion and the H+ (in an acid with acidic hydrogens) are roughly or exactly equal? Such acids would oxidise with both the proton and the anion, and would be of an intermediate class of acids between oxidising and non-oxidising.More
@harry Good point. The standard potential assumes a $\pu{1M}$ concentration of all dissolved ions (including $\ce{H+}$ which maybe doesnt work as well with weak acids. I would have to research what is done in those cases but I am too lazy. As for oxidising anions, I am not aware off the top of my head of any anion that would have an equal oxidising power, but do check the electrochemical series.More
Also, isnt pH=0 and concentration=1M only for strong acids?More
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There is really nothing more to say than what's in the Wikipedia article referred to by the OP and the comments. "Nonoxiding acids" are those acids that react with metals by displacement of hydrogen, such as $\ce{HCl}$ reacting with zinc. "Oxidizing acids" like $\ce{HNO3}$ contain more strongly oxidizing components that react instead of the solvated $\ce{H^+}$, or possibly convert wiuld-be displaced hydrogen back to solvated $\ce{H^+}$.
There is really nothing more to say than what's in the Wikipedia article referred to by the OP and the comments. "Nonoxiding acids" are those acids that react with metals by displacement of hydrogen, such as $\ce{HCl}$ reacting with zinc. "Oxidizing acids" like $\ce{HNO3}$ contain more strongly oxidizing components that react instead of the solvated $\ce{H^+}$, or possibly convert wiuld-be displaced hydrogen back to solvated $\ce{H^+}$.
As an add-on, I'll post an excerpt from the 6th edition of "Chemistry: The Molecular Nature of Matter" by Jespersen et al.
Kudos to Freddy who posted it in the chatroom.
As an add-on, I'll post an excerpt from the 6th edition of "Chemistry: The Molecular Nature of Matter" by Jespersen et al.
Kudos to Freddy who posted it in the chatroom.
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A non-oxidising acid is an acid in which there is no stronger oxidant than $\ce{H+}$ at $\mathrm{pH}\ 0$.
Or, in a slightly different wording, a non-oxidising acid would be one that cannot dissolve any noble metal at $1~\mathrm{M}$ concentration, but should (in the absence of effects like overpotential) dissolve any non-noble metal at that concentration.
Nitric acid has the strong oxidation agent $\ce{NO3-}$ present, which will reduce to $\ce{NO}$ or $\ce{NO2}$ depending on the concentration. It is able to oxidise noble metals such as silver.
Hydrochloric acid, on the other hand, has no other oxidising agent. The chloride ion is already fully reduced. Therefore, it is not able to oxidise noble metals such as copper.
Some acids are more strongly oxidising if they are concentrated. Sulphuric acid is one. Only in higher concentrations will reduction of sulphate to $\ce{SO2}$ take place and make the acid oxidising. In lower concentrations, only $\ce{H+}$ takes part in oxidations.
A non-oxidising acid is an acid in which there is no stronger oxidant than $\ce{H+}$ at $\mathrm{pH}\ 0$.
Or, in a slightly different wording, a non-oxidising acid would be one that cannot dissolve any noble metal at $1~\mathrm{M}$ concentration, but should (in the absence of effects like overpotential) dissolve any non-noble metal at that concentration.
Nitric acid has the strong oxidation agent $\ce{NO3-}$ present, which will reduce to $\ce{NO}$ or $\ce{NO2}$ depending on the concentration. It is able to oxidise noble metals such as silver.
Hydrochloric acid, on the other hand, has no other oxidising agent. The chloride ion is already fully reduced. Therefore, it is not able to oxidise noble metals such as copper.
Some acids are more strongly oxidising if they are concentrated. Sulphuric acid is one. Only in higher concentrations will reduction of sulphate to $\ce{SO2}$ take place and make the acid oxidising. In lower concentrations, only $\ce{H+}$ takes part in oxidations.
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There is really nothing more to say than what's in the Wikipedia article referred to by the OP and the comments. "Nonoxiding acids" are those acids that react with metals by displacement of hydrogen, such as $\ce{HCl}$ reacting with zinc. "Oxidizing acids" like $\ce{HNO3}$ contain more strongly oxidizing components that react instead of the solvated $\ce{H^+}$, or possibly convert wiuld-be displaced hydrogen back to solvated $\ce{H^+}$.
There is really nothing more to say than what's in the Wikipedia article referred to by the OP and the comments. "Nonoxiding acids" are those acids that react with metals by displacement of hydrogen, such as $\ce{HCl}$ reacting with zinc. "Oxidizing acids" like $\ce{HNO3}$ contain more strongly oxidizing components that react instead of the solvated $\ce{H^+}$, or possibly convert wiuld-be displaced hydrogen back to solvated $\ce{H^+}$.
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