When hydrochloric acid (HCl) is added to a beaker, it reacts with the metal or metal oxide present in the beaker to form a salt and water. The specific salt formed depends on the metal present.

For example, if hydrochloric acid is added to a beaker containing sodium metal (Na), the reaction that occurs is:

2Na + 2HCl → 2NaCl + H₂

In this reaction, sodium chloride (NaCl) is formed as the salt.

Similarly, if hydrochloric acid is added to a beaker containing copper(II) oxide (CuO), the reaction that occurs is:

CuO + 2HCl → CuCl₂ + H₂O

In this reaction, copper(II) chloride (CuCl₂) is formed as the salt.

The general reaction between hydrochloric acid and a metal or metal oxide can be represented as follows:

Metal or Metal Oxide + Hydrochloric Acid → Salt + Water

The salt formed in each case depends on the metal or metal oxide present in the beaker.