Question

The density of liquid NH₃ is 0.64 g/mL; the density of gaseous NH₃ at STP is 0.0007 g/mL. Explain the difference between the densities of these two phases.

Answer 1

The density of liquid NH3 is higher than its gaseous form due to the closer proximity of molecules in liquid ammonia, resulting in a greater mass within the same volume compared to the widely spaced molecules in the gaseous state.

Step-by-step explanation:

The density of a substance is a measure of its mass per unit volume. The difference in density between liquid and gaseous NH3 is primarily due to the spacing between ammonia molecules in the different phases. In the liquid state, NH3 molecules are much closer together, meaning more mass is packed into a given volume.

This results in a higher density of 0.64 g/mL for liquid NH3. In contrast, gaseous NH3 molecules are spread out far apart, especially at Standard Temperature and Pressure (STP), which significantly decreases its density to 0.0007 g/mL. It is noteworthy that at STP, any ideal gas, including ammonia, occupies about 22.4 L per mole, contributing to the gas's low density.