Question

$CuO$ reacts with $HCl$ but $Cu$ does not, why?

• A. Copper has a higher reduction potential than hydrogen, it does not react with non-oxidising acids like $HCl$
• B. Copper has a lower reduction potential than hydrogen, it does not react with non-oxidising acids like $HCl$
• C. Copper is a least reactive metal hence does not react with any acid
• D. Both $Cu$ and $CuO$ does not react with $HCl$

Answer 1

Answer: (A)

Copper has a higher reduction potential than hydrogen, it does not react with non-oxidising acids like $HCl$

Copper does not react with $HCl$ acid, but copper oxide does react. Copper has a higher reduction potential than hydrogen, hence it does not react with non-oxidising acids like $HCl$ or dil.$H_{2}S{O}_4$.
But metal oxides are basic substances, and so they generally react with acids forming respective salt and water.