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Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness.Temperature is measured with a thermometer.It reflects the average kinetic energy of the vibrating and colliding atoms making up a substance.
kT (also written as k B T) is the product of the Boltzmann constant, k (or k B), and the temperature, T.This product is used in physics as a scale factor for energy values in molecular-scale systems (sometimes it is used as a unit of energy), as the rates and frequencies of many processes and phenomena depend not on their energy alone, but on the ratio of that energy and kT, that is, on E ...
Such temperature scales that are purely based on measurement are called empirical temperature scales. The second law of thermodynamics provides a fundamental, natural definition of thermodynamic temperature starting with a null point of absolute zero. A scale for thermodynamic temperature is established similarly to the empirical temperature ...
Thermodynamic temperature is a quantity defined in thermodynamics as distinct from kinetic theory or statistical mechanics.. Historically, thermodynamic temperature was defined by Lord Kelvin in terms of a macroscopic relation between thermodynamic work and heat transfer as defined in thermodynamics, but the kelvin was redefined by international agreement in 2019 in terms of phenomena that are ...
The size of helium atoms relative to their spacing is shown to scale under 1,950 atmospheres of pressure. The atoms have an average speed relative to their size slowed down here two trillion fold from that at room temperature. The kinetic theory of gases is a simple classical model of the thermodynamic behavior of gases. Its introduction ...
During the 18th century, multiple temperature scales were developed, [9] notably Fahrenheit and centigrade (later Celsius). These scales predated much of the modern science of thermodynamics, including atomic theory and the kinetic theory of gases which underpin the concept of absolute zero. Instead, they chose defining points within the range ...
These terms are with respect to a given temperature and time scale. A process approaches pure kinetic control at low temperature and short reaction time. For a sufficiently long time scale, every reaction approaches pure thermodynamic control, at least in principle. [11] [12] This time scale becomes shorter as the temperature is raised.
The absolute temperature (Kelvin) scale can be loosely interpreted as the average kinetic energy of the system's particles. The existence of negative temperature, let alone negative temperature representing "hotter" systems than positive temperature, would seem paradoxical in this interpretation.