Question #80627

Elements differ in relative reactivity, it is something often taught in schools as "the reactivity series". In this case, zinc is more reactive than hydrogen, but copper is less reactive than hydrogen. It means that zinc can displace hydrogen from HCl, but copper cannot. Here's why....

If you look at the electron configureation of zinc, it is # [Ar] 3d^10 4s^2# so it has two valance electrons that it readily gives up in order to form aqueous #Zn^(2+)# ions.

On the other hand, copper's electron configuration is #[Ar] 3d^10 4s^1# so in order for copper to be able to behave the same way as zinc, it would need to be able to lose a 2nd electron, which would mean that the 3d sub shell would need to give up an electron, and that isn't favourable energy-wise, as 10 electrons in a 3d shell is already stable.

So that makes zinc generally more reactive than copper, and in relation to hydrogen. So zinc is able to displace hydrogen from HCl, but copper is not.

Here is a video which demonstrates this and also examines the activity of magesium.

Since zinc is located higher than hydrogen in the activity series (which means that it is more reactive than hydrogen), it liberates hydrogen from #"HCl"#.

On the other hand, copper is placed lower than hydrogen in the activity series of metals (which means that it is less reactive than hydrogen) and therefore does not react with #"HCl"#.

Hope u understood! :) ShantanuDash