Which gas is produced when hydrochloric acid reacts with zinc metal? Hydrogen is produced when hydrochloric acid reacts with zinc metal.
The reaction is a single-displacement reaction: zinc atoms give up electrons and become zinc ions, while hydrogen ions from hydrochloric acid gain electrons and pair up as hydrogen molecules. The balanced equation is Zn + 2HCl → ZnCl₂ + H₂. The other product is aqueous zinc chloride.
Visible fizzing occurs because hydrogen gas is released as bubbles. In a school laboratory, the gas can be collected and identified with a lighted splint; hydrogen burns with a characteristic “pop.” This test must be performed under proper supervision because hydrogen is highly flammable, particularly when mixed with air.
The reaction illustrates the activity series of metals. Zinc is more reactive than hydrogen, so it can displace hydrogen from a non-oxidizing acid such as hydrochloric acid. Copper, by contrast, does not normally release hydrogen with dilute hydrochloric acid because it is less reactive than hydrogen. Reaction speed depends on factors such as acid concentration, temperature, zinc surface area and whether the metal surface is clean.