PE When two atoms are bound in a molecule, the interaction between them can some
ID: 1660656 • Letter: P
Question
PE When two atoms are bound in a molecule, the interaction between them can sometimes be modeled by a force that is attractive at long distance and repulsive at short. This interaction can be described by a potential well that looks like the figure at the right. (See Interatomic forces.) The horizontal axis in this graphs represents the distance between the atoms centers. When the atoms are in a bound state, the point on the graph representing the relative position of the atoms will be near the bottom of the well. The higher up it is, the more that atoms will oscillate around their stable point (the minimum of the potential well). A. The CLUE simulation of molecular collisions shows the potential energy between two bound atoms moving in a gas with other atoms. When the simulation starts, the two bound atoms (shown darker than the others) are bound with a relative energy near the bottom of the potential well describing the interaction between them.& As they move around, they may collide with other atoms or molecules and some of the kinetic energy of the other atom may be transferred through the collision into the relative motion of the two bound atoms, setting them oscillating. distance(r) between atomic/molecular centers Consider two situations: one in which the collision adds not enough energy to the relative motion of the two bound atoms to separate them and one in which it adds more than enough to separate them. For both cases, tell the story of what is happening to the relative motion of the two atoms and describe how that motion and change in motion would be represented on the potential energy graph of the relative motion of the two bound (at first) atomsExplanation / Answer
A) The blue dot shows the current state of the system. At the lowest of the potential well, the system does not have any extra energy. In other words, the two molecules are stuck together and do not move relative to each other as their is no extra energy to move.
If a collicion occurs and some energy is transfrred, the blue dot will convert to a horizontal line (something like shown in third figure). In that case, the molecules will still remain bound (as the horizontal line is within the well) but they can move relative to each other corresponding to how far above the horizontal line is shifted from initial blue dot.
If, however, the collison imparts so much energy that the horizontal line goes above the zero level (where the well ends), the molecules will not remain bound to each other. The molecule would then have gotten enough energy to break the bounded state and individual atoms can then start to move freely. This would consume the energy imparted to the molecule.
B) The well in negative x region bounds more strongly as it is deeper. The deeper the well, more is the energy requred to come out of it.
C) Molecule has made a transition to a well that is more strongly bound. Earlier the molecule has in itself more energy (as the potential it was in was higher, check the graph). After the transition, molecule is in a deeper well or, in other words, has even lesser potential energy. The extra energy (actually called chemical energy) mush have gone somewhere. It is indeed imparted to the atom that caused the transition. As a result, the atom would go at a faster speed than before the collision.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.