What is produced when ammonia dissolves in water, according to the fountain experiment?

When ammonia dissolves in water, it reacts to form ammonium hydroxide. This occurs as ammonia (NH₃) interacts with water molecules to produce ammonium ions (NH₄⁺) and hydroxide ions (OH⁻). The presence of hydroxide ions indicates that the solution is basic or alkaline, which is why ammonia solutions are often referred to as ammonium hydroxide, even though it exists mainly as dissolved ammonia with a strong tendency to accept protons from water.

This reaction is significant because it explains the behavior of ammonia in aqueous solutions, where it can act as a weak base. The production of hydroxide ions is what makes the solution alkaline, confirming that ammonia in water creates an environment where the pH increases, aligning with observations from experiments that illustrate the basic nature of ammonia solutions.

The other choices do not accurately represent the chemistry involved. Hydrochloric acid and nitric acid are products formed from other reactions involving different compounds, and while an alkaline solution is a general characteristic of the resulting mixture, it is more precise to refer specifically to ammonium hydroxide as the compound produced during the dissolution of ammonia in water.