Liquids: Chapter 10 Section 2 By: Joey Belsma, Taylor Cocke, Lauren Gordon, Lauren Jackson & Trip Mixon

What is a liquid? [lik-wid] noun: composed of molecules that move freely among themselves but do not tend to separate like those of gases; not gaseous nor solid Definite volume but not a definite shape. Takes the shape of its container The particles in a liquid are constantly in motion and are closer together than gas particles due to a greater attraction between the particles (intermolecular force).

Liquids are Fluids The kinetic-molecular theory of liquids states that the particles within a liquid are not bound together in a fixed position. Fluid: A substance that can flow and therefore take the shape of its container Gases and liquids are fluids

Properties of Liquids Relatively high density Relative incompressibility Ability to diffuse Surface tension Evaporation and boiling Formation of solids

High Density Due to the close arrangement of liquid particles, substances in a liquid state are hundreds of times denser in normal atmospheric pressure than they would be as a gas. Liquid substances are usually only 10% less dense than in a solid state of matter Water is an exception *At the same temperature and pressure, different liquids can differ greatly in density

Relative Incompressibility Liquids are not as compressible as gases because liquid particles are packed closer together. When liquid H2O is at 20 degrees Celsius and is compressed with 1000 atm, the volume only decreases 4%. Gas would be 1/1000 of its volume Pressure from liquids act in all directions

Ability to diffuse The constant motion of liquid particles cause diffusion. Diffusion is slower in liquids than in gases Attractive forces between the particles in liquid slow their movement As temperature increases, diffusion speed increases Average KE (speed of moving particles) is increased

Surface tension Surface Tension: A force that tends to pull adjacent parts of a liquid’s surface together, thereby decreasing surface area to the smallest possible size. Result from the attractive forces between liquid particles Water has the highest surface tension Capillary Action: the attraction of the surface of a liquid to the surface of a solid This attraction pulls the liquid molecules upward along the surface against the pull of gravity Transportation of water from the roots of a plant to its leaves

Evaporation and Boiling Vaporization: the process by which a liquid or solid changes to a gas Evaporation: the process by which particles escape the surface of a nonboiling liquid and enter the gas state Evaporation is a form of vaporization Evaporation occurs because the particles of a liquid have different kinetic energies Boiling: the change of a liquid to bubbles of vapor that appear throughout the liquid

Formation of Solids Freezing: the physical change of a liquid to a solid by removal of energy as heat When a liquid is cooled, the average KE decreases therefore the particles slow down making the substance a solid