Site Loader
Rock Street, San Francisco

  Supervisor: Prof. Mahmoud El-Sayed1. The definition of physical propertiesA physical property is defined as a characteristic of matter that may be observed and measured without changing the chemical identity of the studied sample. The measurement of a physical property may change the arrangement of matter in the sample, but not the structure of its molecules. In other words, a physical property may involve a physical change, but not a chemical change. If a chemical change or reaction occurs, the observed characteristics are chemical properties.2. Types of physical propertiesPhysical properties could be classified as intensive and extensive properties. An intensive property does not depend on the amount of matter in a sample. It is a characteristic of the material. Examples of this class include melting point and density. Extensive properties do depend on sample size. Examples of extensive properties include shape, volume, and mass. How to differ between Intensive and Extensive properties :One easy way to tell whether a physical property is intensive or extensive is to take two identical samples of a substance and put them together. If this doubles the property (e.g., twice the mass, twice as long), it’s an extensive property. If the property is unchanged by altering the sample size, it’s an intensive property. Below examples for physical properties classified as given above.2.1. Intensive properties • State: Metals are solids at room temperature with the exception of mercury, which is liquid at room temperature (Gallium is liquid on hot days).• Luster: The state or quality of shining by reflecting light and can be polished.  Metals have the quality of reflecting light from its surface and can be polished such as gold, silver and copper.• Malleability: the state capability of being shaped, as by hammering or pressing:  Metals have the ability to withstand hammering and can be made into thin sheets known as foils (a sugar cube chunk of gold can be pounded into a thin sheet which will cover a football field).• Ductility: Ductility is a measure of a metal’s ability to withstand tensile stress—any force that pulls the two ends of a material away from each other. • Hardness: is a measure of how resistant solid matter is to various kinds of permanent shape change when a compressive force is applied All metals are hard except sodium and potassium, which are soft and can be cut with a knife.• Conduction: The transfer of energy, such as heat or an electric charge, through a substance. In heat conduction, energy is transferred from molecule to molecule by direct contact; the molecules themselves do not necessarily change position, but simply vibrate more or less quickly against each other. In electrical conduction, energy is transferred by the movement of electrons or ions. Metals are good conductors because they have free electrons. Silver and copper are the two best conductors of heat and electricity. Lead is the poorest conductor of heat. Bismuth, mercury and iron are also poor conductors• Density: a physical property of matter that expresses a relationship of mass to volume. The more mass an object contains in a given space, the more dense it is. Metals have high density and are very heavy. Iridium and osmium have the highest densities whereas lithium has the lowest density.Melting point: Its the temperature where a substance changes phase from solid to liquid. In the case of metal alloys or mixtures, the melting point is a range from where it begins to melt and is finally completely molten.Boiling point: Its the temperature where a substance changes phase from liquid to gas.Note: Metals have high melting and boiling point. Tungsten has the highest melting point where as silver has low boiling point. Sodium and potassium have low melting points.Temperature: It’s a physical quantity that expresses the subjective perceptions of hot and coldElasticity: It is the ability of a body to resist a distorting influence or deforming force and to return to its original size and shape when that influence or force is removed.Brittleness:Tendency of a material to fracture or fail upon the application of a relatively small amount of force, impact, or shock.Sonorous:  capable of giving out a sound, especially a deep, resonant sound, as a thing or place2.2. Extensive properties         Internal energy: is the total energy of a closed system. The change in internal energy (?U) of a reaction is equal to the heat gained or lost (enthalpy change) in a reaction when the reaction is run at constant pressure.Amount of substance: is a standards-defined quantity that measures the size of an ensemble of elementary entities, such as atoms, molecules, electrons, and other particles. It is sometimes referred to as chemical amountEnergy: is defined as the capacity of a physical system to perform workVolume: refers to the amount of space the object takes up. In other words, it’s a measure of the size of an object, just like height and width are ways to describe size.Entropy : A function of thermodynamic variables, as temperature, pressure, or composition, that measures the energy that is not available for work during a thermodynamic process. A closed system evolves toward a state of maximum entropy. Enthalpy : A quantity associated with a thermodynamic system, expressed as the internal energy of a system plus the product of the pressure and volume of the system, having the property that during an isobaric process, the change in the quantity is equal to the heat transferred during the process.

Post Author: admin

x

Hi!
I'm Dora!

Would you like to get a custom essay? How about receiving a customized one?

Check it out