Liquids

What is a Liquid? ● A Liquid is a form of matter that has a definite volume but does not have a definite shape ● Because of its lack of shape, liquids can therefore take the shape of any container. ● Like a gas, particles in liquids are in constant motion. But the particles in liquids are closer together and so the attractive forces between a liquid’s particles are more effective.

The Kinetic-Molecular Theory in Liquids Liquids are more ordered than gases because of the stronger molecular forces and the lower mobility of the liquid particles. According to the Kinetic-molecular theory of liquids, particles are not bound together but are instead in constant motion. Because of this particle mobility, liquids and gases are referred to as fluids. A substance that can flow and therefore take that shape of its container.

Density of Liquids At normal atmospheric pressure, most substances are hundreds of times denser in liquid state than in gas states. This higher density is a result of the close arrangement of liquid particles, most substances are only slightly less dense in liquid state that in solid states. This difference between densities is the reason why ping-pong balls and soccer balls can float, because the air inside the balls is less dense than the liquids.

Incompressibility of Liquids Liquids not very compressible because their particles are closely packed together. Such behavior is typical of all liquids and is similar to the behavior of solids. Liquids are much less compressible than gases because gas particles are very spread out, but like gases, liquids can transmit pressure equally in all directions.

Liquid’s Ability to Diffuse Any liquid gradually diffuses and mixes with other liquids in which it can be dissolved. The constant random motion of particles causes diffusion in liquids as it does in gases, yet the diffusion is much slower in liquids than in gases because liquid particles are closer together. As the temperature of a liquid is increased, diffusion occurs more rapidly, this is because the average kinetic energy, and therefore the average speed of the particles is increase.

Surface Tension of Liquids Surface tension is a force that tends to pull adjacent parts of a liquid’s surface together, thereby decreasing surface area to the smallest possible size. Surface tension results from the attractive force forces between particles of a liquid; the higher the force attraction, the higher the surface tension. Capillary action is the attraction of the surface of a liquid to the surface of a solid, and it is closely related to surface tension. Capillary action tends to pull liquids up the surface of a tube and is also responsible for the transportation of water from the roots of a plant to its leaves. Hypocitaminosises - Lack of essential vitamins

Evaporation and Boiling of Liquids The process by which a liquid or solid changes to a gas is vaporization; evaporation is the process by which particles escape from the surface of a non-boiling liquid and enter the gas state. Evaporation occurs because the particles of a liquid have different kinetic energies. Particles with higher-than-average energies move faster. Some particles with higher-than-average energies can overcome the intermolecular forces that bind them to the liquid and escape into the gas state.

Formation of Solids From Liquids When a liquid is cooled, the average energy of its particles decrease. If the energy is low enough, attractive forces pull the particles into an orderly arrangement, the the liquid becomes a solid. The physical change of a liquid to a solid by removal of energy as heat is called solidification or freezing.