Question

practice: states of matter
answer the following questions. you may need a separate sheet of paper.

1. list the three principles of the kinetic molecular theory.
2. consider the particles that make up solids, liquids, and gases. how would you describe how they are moving in each of these states of matter?
3. describe the movement of particles at the melting - point of a substance. consider what is happening with temperature and energy.
4. describe the movement of the particles at the boiling point of a substance. consider what is happening with temperature and energy.

acetic acid has a melting point of 16.6°c and a boiling point of 117.9°c. sketch a heating curve showing phase changes of acetic acid. clearly label all 7 parts like we did in our notes.

Explanation:

1. The three principles of kinetic - molecular theory: Matter is made of particles in constant motion; the speed of particles increases with temperature; particles have forces of attraction and repulsion between them.
2. In solids, particles vibrate in fixed positions; in liquids, particles move more freely than in solids but are still close together; in gases, particles move rapidly and are far apart.
3. At the melting point, particles gain enough energy to break free from their fixed positions in the solid state and start to move more freely as a liquid. Temperature remains constant during melting as energy is used for phase - change.
4. At the boiling point, particles have enough energy to completely break the intermolecular forces and become a gas. Temperature remains constant during boiling as energy is used for the phase - change from liquid to gas.

Answer:

1. Matter is made of moving particles; particle speed increases with temperature; particles have inter - particle forces.
2. Solids: vibrate in place; Liquids: move more freely; Gases: move rapidly and are far apart.
3. Particles gain energy to change to liquid; temperature is constant during melting.
4. Particles have enough energy to become gas; temperature is constant during boiling.