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A frigorific mixture may be used to obtain a liquid medium that has a reproducible temperature below ambient temperature. Such mixtures were used to calibrate thermometers. In chemistry a cooling bath may be used to control the temperature of a strongly exothermic reaction. A frigorific mixture may be used as an alternative to mechanical ...
Additionally, no external chiller bath or refrigeration unit is needed. D5773 is capable of determining cloud point within a temperature range of -60 °C to +49 °C. Results are reported with a temperature resolution of 0.1 °C. Under ASTM D5773, the test sample is cooled by a Peltier device at a constant rate of 1.5 +/- 0.1 °C/min.
The Fermi temperature is defined as this maximum energy divided by the Boltzmann constant, and is on the order of 80,000 K for typical electron densities found in metals. For temperatures significantly below the Fermi temperature, the electrons behave in almost the same way as at absolute zero.
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
A definition of temperature can be based on the relationship: = The relationship suggests that a positive temperature corresponds to the condition where entropy, S, increases as thermal energy, q rev, is added to the system. This is the "normal" condition in the macroscopic world, and is always the case for the translational, vibrational ...
These dimensionless thermodynamic coordinates, taken together with a substance's compressibility factor, provide the basis for the simplest form of the theorem of corresponding states. [1] Reduced properties are also used to define the Peng–Robinson equation of state, a model designed to provide reasonable accuracy near the critical point. [2]
Since 1982, STP has been defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 1 bar (100 kPa, 10 5 Pa). NIST uses a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 1 atm (14.696 psi, 101.325 kPa). [3] This standard is also called normal temperature and pressure (abbreviated as NTP).
On the empirical temperature scales that are not referenced to absolute zero, a negative temperature is one below the zero point of the scale used. For example, dry ice has a sublimation temperature of −78.5 °C which is equivalent to −109.3 °F. [97] On the absolute Kelvin scale this temperature is 194.6 K.