Bellringer If we applied kinetic-molecular theory to liquids and solids, how would you re-word the three basic assumptions of the theory?

Liquids and Solids Objectives: 1. State the kinetic theory of matter. 2. Use the kinetic theory to explain states of matter.

The Kinetic-Molecular Theory  Def. (again!): describes the behavior of gases in terms of particles in motion  Can be applied to liquids and solids; however, you must also consider the forces of attraction between the particles. (What kind of forces are these?)

Liquids  Like gases, liquids take the shape of their container.  Unlike gases, the attractive (intermolecular) forces keep the particles closely packed (given liquids a fixed volume).

Behavior of Liquids:  Can liquids and gases of the same substance have the same temperature? 1.Density and Compression:  Density of liquids is much greater than that of gases, AT THE SAME TEMPERATURE AND PRESSURE.  Since KE (and temperature) is the same, what can account for the difference in density?  Liquids CAN be compressed, but not very much. Why not?

Behavior of Liquids: 2.Fluidity: ability to flow  Both gases and liquids are considered fluids. Why?  Can a liquid diffuse?  Which is more fluid, a gas or a liquid? 3.Viscosity: a liquid’s resistance to flow  What do you think would affect (increase) a liquid’s viscosity?

Behavior of Liquids: 4.Surface tension:  Def: the energy required to increase the surface area of a liquid by a given amount  Particles in the middle of a liquid can be attracted to particles to the side, above, and below them. What about the particles at the surface?  The stronger the intermolecular forces, the greater the surface tension.

Water Domes Mini-Lab 1.See how many drops of water you can get on the penny. (Drops must free fall!!!) 2.Dry off the penny and build a 20-drop water dome on it. 3.If you poke it with a clean, dry pin, does this break the cohesive (attractive) bonds b/t water molecules? 4.Dip the pin in liquid soap and poke the water dome. What happens? 5.How does soap affect surface tension? Propose an explanation for WHY.

Solids  According to kinetic-molecular theory, the kinetic energy of a mole of a solid substance is the SAME as a mole of the same liquid substance AT THE SAME TEMPERATURE.  So why does the solid have a definite shape and volume? Answer: Strong intermolecular forces in the solid limit the motion of the particles to “vibrations around fixed locations”.

Solids, continued……  How does density of a solid usually compare to that of the same liquid?  Can solids be compressed?  Are solids fluid?