Question

the H2 molecules hydrogen gas have lower potential energy than the hydrogen molecules in water

Answer 1

Solution : Hydrogen H2 molucule is an example of an element that exists naturally as a diatomic molecule. A diatomic molecule is a molecule containing two atoms. These H2 molecules have lower potential energy than the hydrogen molecules in water because when they are bonded to other atoms than when they are separated. Consider two isolated hydrogen atoms that are separated by a distance large enough to prevent any interaction between them. At this distance, the potential energy of the system is said to be equal to zero (see figure below).

Repulsion No overlap: no attraction Potential Energy Some overlap: some attraction Internuclear distance

As the atoms approach one another, their electron clouds gradually begin to overlap. Now there are several interactions which begin to occur. One is that the single electrons that each hydrogen atom possesses begin to repel each other. This repulsive force would tend to make the potential energy of the system increase. However, the electron of each atom begins to be attracted to the nucleus of the other atom. This attractive force tends to make the potential energy of the system decrease.