Final answer:
In the reaction between zinc and hydrochloric acid, vigorous bubbling due to the production of hydrogen gas is observed, indicating a chemical reaction forming zinc chloride and hydrogen gas.
Step-by-step explanation:
When zinc is combined with hydrochloric acid, the observation is a vigorous bubbling reaction. This bubbling is due to the production of hydrogen gas, which indicates a chemical reaction taking place. In this reaction, zinc reacts with hydrochloric acid to form an aqueous solution of zinc chloride and release hydrogen gas. The balanced chemical equation for this reaction is:
Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g)
This is a single-displacement reaction, and it is important to observe the experiment carefully for safety as hydrogen gas is flammable. Other observations such as temperature changes and the disappearance of the zinc metal can also occur during the reaction.