Question

1. Describe and compare the motion and interactions of molecules in the three different phases of matter 2. Explain the relationship between temperature and intermolecular forces as it affects the phase of matter. 3. List the steps necessary to determine the intermolecular forces present in a pure substance.

Answer 1

In solid phase, the molecules are closely bound to one another and thus have strong molecular interactions in comparison to liquid and gas phase.. As the molecules are tightly packed thus giving a fixed shape to solids.

In gases molecular forces are weak and the molecules can move freely as compared to the rest of the two.

So interactions are more in solids than in liquids and than in gases.the order of motion of molecules is just its reverse.

2.

Increased temperature does not weaken intermolecular forces, but it does give the molecules more kinetic energy When you increase temp you are actually increasing the motion of particles, which would require stronger forces to hold the particles together. The motion (temp) will eventually overcome the force, causing a phase change. Now, keep in mind that the temp of a substance will not change while it is undergoing a phase change because the added energy is overcoming the intermolecular forces.

When you heat an ice cube above 0 °C, it melts. The water molecules have enough kinetic energy to overcome the attractions of their neighbours. They move from the solid phase to the liquid phase.