Why does copper not replace hydrogen from acids?

Copper does not replace hydrogen from acids because it is less reactive than hydrogen. The reactivity of metals determines their ability to displace hydrogen from acids. Metals higher in the reactivity series can replace hydrogen from acids, while metals lower in the series cannot.

Hydrogen is placed at the top of the reactivity series because it is a non-metal, despite its position in the periodic table. It tends to lose electrons and form positive ions (H+). Metals like copper, on the other hand, are placed below hydrogen in the reactivity series.

Copper is a moderately reactive metal, but it is not reactive enough to displace hydrogen from most acids. When copper is placed in an acid such as hydrochloric acid (HCl) or sulfuric acid (H2SO4), it does not readily replace the hydrogen ions in the acid solution. This is because copper's reactivity is lower than that of hydrogen.

The reactivity of metals is related to their ability to lose electrons and form positive ions. Metals with higher reactivity have a greater tendency to lose electrons and form positive ions. Copper, although it can react with certain acids under specific conditions, does not displace hydrogen from acids in a typical scenario due to its relatively lower reactivity compared to hydrogen.