Tin is placed in dilute hydrochloric acid. what happen to the solution and to the metal?

Question

Is there any remains of tin metal in the container in the end?

Answer 1

The tin will dissolve in the acid in a simple single replacement reaction. This can be seen from the activity series of metals or from reduction potentials: tin is more active than hydrogen. It depends on how much tin you use. Obviously, if you add a pound of tin and only a few drops of acid, there will be tin left over. With the stoichiometric amount of tin or smaller, there will ideally be no tin left over, but the reaction is rather slow (especially with the dilute acid).

The tin reacts as follows:

Sn + 2H+ ------> Sn2+ + H2

If there is enough tin to use up a substantial amount of the acid, the Sn2+ will hydrolyze:

Sn2+ + 2H2O <-----> Sn(OH)2 + 2H+

When I tried dissolving lead free solder (96pct tin) in fairly concentrated acid, I observed no reaction after a few hours, but this could have been from the silver (4pct) forming a protective layer. When I precipitated crystals of tin metal from a solution of SnCl2, to which I had added HCl to prevent the hydrolysis of the salt, the crystals would dissolve a few hours after forming if left in the solution. So the reaction is slow, but still occurs.