[hongkongrubbish]

If yes,
I wonder why Cu will not react with HCl but CuO will ,
what are the principles behind?

[Albert]

Yes, it does: 2 HCl + CuO —> CuCl₂ + H₂O

Copper doesn't react with non-oxidizing acids, such as HCl, in the absence of oxigen. However, if exposed to air, the following reaction takes place:

2 Cu + O₂ + 4 H₃O⁺ -> 2 Cu²⁺ + 6 H₂O

[hongkongrubbish]

However, if exposed to air....

um... Thanks first

 but "exposed to air" means we need to pump air into the acid or just place it under normal conditions...?

normally there is oxygen in the solution, so will there be any reactions  ?

[Albert]

In a solution the reaction actually takes place...slowly. Spraying an aqueous solution of an acid on, say, a copper layer means you have the same reaction with a different timing.

[hkalfighter]

is CuO amphoteric ? i see some covalent oxides such as BeO , Al2O3 and ZnO are amphoteric and they react with acid to give metal ions and water but i don't know if CuO behaves the same
the reaction is like BeO + 2H+ > Be2+ + H2O
by the way , i m from Hong Kong too , are u A Level student ?

[Alberto_Kravina]

CuO is not amphoteric

amphoteric oxides

[hkalfighter]

oh , thanks a lot

[hongkongrubbish]

is CuO amphoteric ? i see some covalent oxides such as BeO , Al2O3 and ZnO are amphoteric and they react with acid to give metal ions and water but i don't know if CuO behaves the same
the reaction is like BeO + 2H+ > Be2+ + H2O
by the way , i m from Hong Kong too , are u A Level student ?

haha I am from HK...but sitting for CE 
rare to have HK students here 

[hongkongrubbish]

However, if exposed to air....

um... Thanks first

 but "exposed to air" means we need to pump air into the acid or just place it under normal conditions...?

normally there is oxygen in the solution, so will there be any reactions  ?

btw, can we say that the CuO is basic, and thus neutralization occurs?
because a book tells me that the metals will increase the properties of being a base across the periodic tabe (from right to left) if become oxides
is that true?

Thanksss !

[kkrizka]

btw, can we say that the CuO is basic, and thus neutralization occurs?
because a book tells me that the metals will increase the properties of being a base across the periodic tabe (from right to left) if become oxides
is that true?

Yes, the O^2- in the oxide is a string base. It reacts with water as in the following equation:
O^2-+H₂O->2OH^-

All the O^2- will react, but you also have to know the solubility of the oxide to figure out how much of the O^2- is avalible for the above reaction.

[hkalfighter]

how about the mechanism ? does the negative O oxide ion attack the H on H2O to give OH- ?

[Alberto_Kravina]

how about the mechanism ? does the negative O oxide ion attack the H on H2O to give OH- ?

Yes! It is a very strong base - it attracts the H-atom of H₂O to form the OH^- ion