The liquid state of matter is a transitional condition between solids and gases. Particles in a liquid, like solid particles, are susceptible to intermolecular attraction; but, because liquid particles have more space between them, they are not locked in a fixed position. The attraction between the particles in a liquid maintains the liquid’s volume constant. In solids, molecules are placed very close to each other while the distance increases from liquids to gases. Here we are going to focus the general properties of liquids that all of them possess, including physical and chemical properties.
Density of liquids is usually close to that of a solid and much higher than that of a gas. As a result, both liquid and solid are classified as condensed matter. However, because liquids and gases both have the potential to flow, they are both referred to as fluids. Although liquid water is plentiful on Earth, it is the least frequent form of matter in the known universe because liquids require a relatively limited temperature/pressure range to exist. The majority of known stuff in the cosmos is in the form of gaseous interstellar clouds or plasma from within stars.
The mobility of the particles causes the liquid’s form to change. Liquids will flow and fill the bottom portion of a container, assuming the shape of the container but not changing in volume. Because of the little amount of space between particles, liquids have relatively limited compressibility. Some common properties of liquids are as following:
- Liquids flow from higher to lower level.
- Liquids are virtually incompressible. Molecules in liquids are very near to one another. There isn’t a lot of space between the molecules. The molecules cannot be pressed closer together.
- Liquids have a constant volume.
- Liquids have no defined shape, they take the shape of container. If you pour 100 ml of water into a cup, it will take the shape of cup. Pour the liquid from the cup into the bottle; the liquid will change shape and now has the shape of bottle.
- Under typical situations, liquids have boiling points that are higher than room temperature. When liquids are heated, they gradually transform into vapor or gaseous phases. This is known as boiling.
- Static liquids, in uniform gravitational fields exhibit buoyancy, which occurs when objects immersed in the liquid experience a net force due to pressure change with depth. The magnitude of the force is proportional to the weight of the liquid displaced by the object, and the direction of the force is proportional to the average density of the immersed object. If the density of the object is less than that of the liquid, the buoyant force points upward, and the object floats; if the density is greater, the buoyant force points downward, and the object sinks. This is referred to as Archimedes’ principle.
Properties of liquids
What is capillary action?
Capillary action is the rise of liquids through a thin tube, cylinder or permeable substance as a result of adhesive and cohesive forces engaging between the liquid and the surface. Capillarity occurs when the intermolecular bonding of a liquid is significantly inferior to the surface of the substance with which it is interacting. The amount of liquid elevated will also be determined by the diameter of the container as well as gravitational forces.
Cohesive and adhesive forces
Because cohesive and adhesive forces are connected with bulk features, they are inapplicable to discussions of atomic and molecular properties. When a liquid comes in contact with a surface (such as the walls of a graduated cylinder or a tabletop), it is subjected to both cohesive and adhesive forces. These forces determine the form of the liquid.
What is angle of contact?
Contact angle is a typical method for determining the wettability of a surface or a material. Wetting is the study of how a liquid spreads out after being deposited on a solid (or liquid) substrate, or the capacity of liquids to form boundary surfaces with solid states. The greater the wetting tendency, the smaller the contact angle or surface tension.
It is the angle enclosed between the tangent to liquid surface and solid surface which are in contact. Contact angle varies between 0o to 180o. For the liquids, which can wet the surface like water and glass, its value is acute. For the liquids which don’t wet the solid surface, like mercury and glass, its value is obtuse.
Surface tension of liquids
Surface tension is one of the most important properties of liquids. The energy required to raise the surface area of a liquid due to intermolecular forces is referred to as surface tension. Because these intermolecular pressures differ based on the composition of the liquid (e.g. water vs. gasoline) or the solutes in the liquid (e.g. surfactants such as detergent), each solution has a different surface tension.
Surface tension is a feature of a liquid surface that manifests itself as if it were a stretched elastic membrane. This effect can be seen in the roughly spherical shape of small liquid drops and soap bubbles. Certain insects can float on the surface of water due to this feature. The surface tension of water can also support a razor blade. The razor blade does not float: it sinks into the water when pushed through the surface.
What is vapor pressure?
Pressure is the average force exerted by a material (gas, liquid or solid) on a surface, such as the walls of a container or another restricting limit. The pressure of a vapor in thermodynamic equilibrium with its condensed phases in a confined container is known as vapor pressure. All liquids and solids have the tendency to evaporate or sublime into a gaseous state and all gases have the tendency to condense back into their liquid or solid state. Vapor pressure of a closed system can be increased by increasing its temperature.
Viscosity of liquids
Properties of liquids: Another form of bulk attribute is viscosity, which is defined as a liquid’s reluctance to flow. When the intermolecular forces of attraction within a liquid are strong, the viscosity increases. Consider a race between two liquids down a windshield as an example of this phenomenon. Which do you think will roll down the windshield faster, honey or water? Obviously, one would expect water to quickly speed right past the honey, revealing that honey has a far higher viscosity than water. It is also defined as the amount of force required to slide one layer of liquid to the other layer.
A material is called a wetting agent if it reduces the surface tension of a liquid, allowing it to spread more freely. Wetting agents are also known as surfactants. They are the chemical compound that improve the spreading and penetrating qualities of a liquid by lowering its surface tension—the tendency of its molecules to stick to each other. Water’s high surface tension is a difficulty in many applications that require water spreading and penetration. Paints and other coating formulas, detergents, insecticides and other substances fall under this category.
Evaporation of liquids
One of the most common properties of liquids is its evaporation. Because liquid particles are in constant motion, they will clash with one another and with the container’s sides. Collisions of this type transfer energy from one particle to another. When enough energy is transmitted to a particle at the liquid’s surface, it eventually overcomes the surface tension that holds it to the rest of the liquid. When surface particles obtain enough kinetic energy to depart the system, they evaporate. As the faster particles escape, the remaining particles have lower average kinetic energy and the temperature of the liquid cools. This phenomenon is known as evaporative cooling.
The process of transforming a liquid into a gas is known as vaporization. It is also known as evaporation. Because we know that the particles of a gas move faster than those of a liquid, we must assume that an energy input is required for a liquid to become a gas. Heat is the most typical approach to add energy to a liquid system. The molecules in a liquid begin to move quicker as it accumulates energy. If a molecule on the liquid’s surface has enough energy, it can break off and become a gas molecule. The stronger the intermolecular interactions that hold a liquid together, the more energy is required to separate them. What this means in practical terms is that a liquid with strong intermolecular forces will have to be heated to a higher temperature before it will evaporate.
What is condensation?
The process by which a gas transforms from a gas to a liquid. This is the inverse of vaporization. To transform a liquid into a gas, you must first add energy to it, and then remove energy from the gas to convert it back into a liquid. The amount of energy required to transition from gas to liquid phase is the same as that required to transition from liquid to gas phase, except in the opposite sign. As a result, the Heat of Vaporization is the same for both processes, but it is positive (endogenic/endothermic) for evaporation and negative (exergonic/exothermic) for condensation.
What is volatility?
Properties of liquids include volatility which is defined as the likelihood of a substance to vaporize at normal temperatures. Volatility is more commonly associated with liquids, however some highly volatile solids can sublime at ambient temperature. Sublimation occurs when a substance makes transition from solid to gas without first passing through the liquid state.
When a liquid evaporates inside a closed container, the particles are trapped and cannot escape. Some of the evaporated particles will eventually make contact with the remaining liquid and lose enough energy to condense back into it. When the rates of evaporation and condensation are equal, there is no net loss in the amount of liquid.