State Functions Temperature

What is Temperature

Temperature is a physical quantity that describes how hot or cold something is. When a body comes into contact with another that is colder or hotter, it is the manifestation of thermal energy, which is present in all matter and is the source of the occurrence of heat, a flow of energy. Heat should not be confused with temperature.

Temperature is important in many fields, including physics, chemistry, Earth science, astronomy, medicine, biology, ecology, material science, metallurgy, mechanical engineering, and geography, as well as most aspects of everyday life. In most parts of the world, the Celsius scale (°C) is used to measure temperature. It is an empirical scale that was developed by historical progress, with its zero point being defined by the freezing point of water and additional degrees defined so that the boiling point of water was defined at 100 °C, both at sea-level atmospheric pressure.

State Functions Temperature

Temperature is an example of a state function. The net change in temperature is only dependent on the initial and final states of the system, no matter how many times we heat, cool, expand, compress, or otherwise change the system. The volume, pressure, and number of moles of gas in the sample are all the same. A state function is a property that is dependent on a system’s state but independent of the path taken to get there. e.g., temperature and pressure are state functions

State functions include density, internal energy, enthalpy, and entropy. For path functions, such a relationship can’t be written because the limiting states can’t be defined. Path functions are influenced by the path taken between two states.

The average kinetic energy of the atoms or molecules in the system

The average kinetic energy of the atoms or molecules in a system is measured by temperature. Because no heat is transferred between two objects in thermal equilibrium, the zeroth law of thermodynamics states that they are at the same temperature.

The average kinetic energy for the most densely populated energy band can be calculated using a “particle in a box” model of metal holding its conduction electrons within the boundary walls, but without taking into account the lattice’s actual periodic potential energy. The free-electron model, a simple approach, frequently yields surprisingly accurate quantitative values for a number of physical properties of metals related to conduction electrons.

Kinetic theory gives a microscopic account of temperature for some bodies of matter, particularly gases, based on the fact that macroscopic systems are made up of many microscopic particles, such as molecules and ions of various species, with the particles of each species being identical. It uses the classical mechanics of microscopic particles to explain macroscopic phenomena. The equipartition theorem of the kinetic theory states that each classical degree of freedom of a freely moving particle has average kinetic energy. The speed of sound in a gas can be calculated using the molecular character of the gas, temperature and pressure, and Boltzmann’s constant value. Using the value of Boltzmann’s constant as a primary, precisely defined reference, a speed measurement can be made.

Temperature is a state function in thermodynamics.

Heat has a very specific meaning in thermodynamics that differs from how we might use the word in everyday speech. Heat is defined by scientists as the transfer of thermal energy between two systems that are at different temperatures and come into contact. Heat is measured in Joules and is written with the symbol q, or Q. Heat is sometimes referred to as a process quantity because it is defined in the context of an energy transfer process. We’re not talking about the heat contained in a cup of coffee, but we can discuss the heat transferred from the cup of hot coffee to your hand. Because heat is a broad property, the temperature change caused by heat transfer to a system is proportional to the number of molecules in the system.

For two reasons, the thermodynamic temperature is said to be absolute. The first is that its formal character is unaffected by the properties of specific materials. The other reason is that its zero is absolute in the sense that it indicates the absence of microscopic classical motion of the constituent particles of matter, resulting in a limiting specific heat of zero for zero temperature, as stated by the third law of thermodynamics. Nonetheless, a thermodynamic temperature has a numerical value that has been determined arbitrarily by tradition and is dependent on the properties of specific materials.

Conclusion

The Kelvin scale is defined in terms of microscopic phenomena, which are described using statistical mechanics. The International System of Units had previously defined a scale and unit for the kelvin as a thermodynamic temperature by using the reliably reproducible temperature of the triple point of water as a second reference point, with the first reference point being 0 K at absolute zero.