Metals to the left of hydrogen in the electrochemical series react with hydrochloric acid. These elements include lithium, potassium, calcium, sodium, magnesium, aluminum, zinc, iron and lead. Metals to the right of hydrogen in the electrochemical series, such as copper, silver and gold, do not react.
Metals to the left of hydrogen in the series lose electrons when they ionize, whereas those to the right, which do not react with hydrochloric acid, gain electrons when they ionize. When added to hydrochloric acid, the metals that lose electrons are able to produce hydrogen gas and a chloride solution. For example, the combination of magnesium with hydrochloric acid creates magnesium chloride and hydrogen.
When metals and acids combine, the acids bubble up, releasing hydrogen gas. The released gas can be ignited if it is released into an oxygenated environment. The aggressiveness of the reaction is measured by the amount of time it takes for gas to escape the solution. The more bubbles appear, the faster the gas escapes the mixture. Magnesium reacts very quickly when added to hydrochloric acid. In contrast, when lead is combined with hydrochloric acid, the reaction occurs very slowly. When hydrochloric acid is combined with copper, there is no reaction.