When an acid reacts with ammonia, what is formed?

When an acid reacts with ammonia, an ammonium salt is formed due to a neutralization reaction between the two substances. Acids release hydrogen ions (H⁺) when dissolved in water, while ammonia (NH₃) acts as a base by accepting these hydrogen ions. When ammonia accepts a proton from the acid, it forms ammonium ions (NH₄⁺). The overall reaction leads to the formation of the corresponding ammonium salt, which is a product of the acid-base reaction.

For instance, if hydrochloric acid (HCl) reacts with ammonia, the resulting product would be ammonium chloride (NH₄Cl). This reaction illustrates the typical behavior of a Brønsted-Lowry acid-base reaction, where the acid donates protons and the base accepts them, ultimately forming salt and often water.

In this context, the other choices represent different concepts that do not apply to the specific reaction between an acid and ammonia. Carbon dioxide is typically produced in reactions involving carbonates or during combustion, while hydrogen gas is produced in certain metal-acid reactions. An alkali solution refers to a solution containing a base, which is not the product formed when an acid reacts with ammonia.