Phase Changes and Atomic Movement

The video tutorial covers identifying true statements about the movement of molecules in solids and liquids, understanding the phase diagram of carbon dioxide, and the conditions under which it becomes a supercritical fluid. It explains phase transitions such as sublimation, melting, and boiling. Finally, it demonstrates how to determine the formula of a compound based on its lattice structure, focusing on face-centered cubic lattices and tetrahedral holes.

Which statement about the movement of atoms in solids is correct?

• Atoms in solids are relatively stationary.

• Atoms in solids have no movement at all.

• Atoms in solids move rapidly.

• Atoms in solids move freely.

What happens to the molecules of a liquid when it is heated?

• They remain unchanged.

• They slow down.

• They stop moving.

• They speed up.

What is the triple point in a phase diagram?

• The point where only the solid phase exists.

• The point where solid, liquid, and vapor phases coexist.

• The point where only the liquid phase exists.

• The point where only the vapor phase exists.

At what conditions does carbon dioxide become a supercritical fluid?

• Below 73 atmospheres and 304.25 K

• Above 73 atmospheres and 304.25 K

• Below 73 atmospheres and above 304.25 K

• At exactly 73 atmospheres and 304.25 K

What is the transition from solid to gas called?

• Boiling

• Sublimation

• Melting

• Condensation

What is the transition from solid to liquid known as?

• Melting

• Sublimation

• Freezing

• Boiling

What is the transition from liquid to gas called?

• Freezing

• Sublimation

• Boiling

• Melting

In a face-centered cubic lattice, how many atoms are there per unit cell?

• 1

• 2

• 3

• 4

How many tetrahedral holes are filled in the compound described?

• All of them

• None of them

• Half of them

• A quarter of them

What is the reduced formula for the compound with elements A and B?

• A3B3

• A4B4

• AB

• A2B2