Liquids Chapter 10 Section 2

Properties of Liquids Properties are examined relative to the kinetic-molecular theory. The particles of a liquid are closer together than they are in a gas. The attractive forces are more effective. However, the particles are not stuck together in fixed positions.

The movement of the particles explains why liquids and gases are referred to as fluids Fluid: a substance that can flow and therefore take the shape of its container.

Liquid Density Higher density than gases because the particles are closer together

Relative Compressibility Liquids are much less compressible than gases because the liquid particles are already very close together . Liquids, like gases, exert pressure against the sides of the container.

Ability to Diffuse Liquids diffuse and mix with other liquids Diffusion is slower with liquids than gases because the particles move slower. Increase temperature = increase rate of diffusion This is because the average kinetic energy of the particles increases. Demo here on diffusion with beaker of water and food coloring

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 The higher the intermolecular forces, the higher the surface tension. Surface tension causes liquid droplets to take on a spherical shape (smallest possible surface area).

Capillary Action Capillary action: the attraction of the surface of a liquid to the surface of a solid The liquid will rise in a narrow tube. This action is partly responsible for the transportation of water from roots to leaves of a plant. Causes the meniscus in a graduated cylinder

Evaporation and Boiling Vaporization: the process by which a liquid (or a solid) changes to a gas Evaporation: the process by which particles escape from the surface of a nonboiling liquid and enter the gas state Boiling: the change of a liquid to bubbles of vapor that appear throughout the liquid

Formation of Solids When a liquid is cooled, the average energy of its particles decreases. Freezing: (AKA solidification) the physical change of a liquid to a solid by removal of energy as heat All liquids freeze, but some at very low temperatures.