Various kinds of Temperatures we get in Standard 11 - 12 course
While studying for IIT-JEE thoroughly, within standard 11-12 course we get names of a few temperatures. Let us list them in reverse order of common knowledge.
1 ) Krafft Temperature – This is the least known temperature by the students. The Krafft temperature (also known as Krafft point, or critical micelle temperature) is the minimum temperature at which surfactants form micelles. Below the Krafft temperature, there is no value for the critical micelle concentration (CMC), i.e., micelles cannot form. The Krafft temperature is a point of phase change below which the surfactant remains in crystalline form, even in aqueous solution.
Surfactants in such a crystalline state will only solubilize / gather and form micelles if another surfactant assists it in overcoming the forces that keep it crystallized, or if the temperature increases, thus causing entropy to have a stronger force and encouraging the crystalline structure to break apart.
The Krafft point is named after German chemist Friedrich Krafft.
2 ) Inversion Temperature - In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect, Kelvin–Joule effect, or Joule–Thomson expansion) describes the temperature change of a gas or liquid when it is forced through a valve or porous plug while kept insulated so that no heat is exchanged with the environment. This procedure is called a throttling process or Joule–Thomson process.
At room temperature, all gases except hydrogen ( H ), helium ( He ) and neon ( Ne ) cool upon expansion by the Joule–Thomson process. The effect is named after James Prescott Joule and William Thomson, 1st Baron Kelvin, who discovered it in 1852. It followed upon earlier work by Joule on Joule expansion, in which a gas undergoes free expansion in a vacuum and the temperature is unchanged, if the gas is ideal.
The adiabatic (no heat exchanged) expansion of a gas may be carried out in a number of ways. The change in temperature experienced by the gas during expansion depends not only on the initial and final pressure, but also on the manner in which the expansion is carried out.
• If the expansion process is reversible, meaning that the gas is in thermodynamic equilibrium at all times, it is called an isentropic expansion. In this scenario, the gas does positive work during the expansion, and its temperature decreases.
• In a free expansion, on the other hand, the gas does no work and absorbs no heat, so the internal energy is conserved. Expanded in this manner, the temperature of an ideal gas would remain constant, but the temperature of a real gas may either increase or decrease, depending on the initial temperature and pressure.
• The method of expansion discussed in this article, in which a gas or liquid at pressure P1 flows into a region of lower pressure P2 via a valve or porous plug under steady state conditions and without change in kinetic energy, is called the Joule–Thomson process. During this process, enthalpy remains unchanged
The inversion temperature in thermodynamics and cryogenics is the critical temperature below which a non-ideal gas (all gases in reality) that is expanding at constant enthalpy will experience a temperature decrease, and above which will experience a temperature increase. This temperature change is known as the Joule-Thomson effect, and is exploited in the liquefaction of gases. As per the scientific paper that I read, For He Ti is close to 200 ± 50 K, Neon Ti is 870 ± 390 K, Argon Ti 3800 ± 1800 K, For Hydrogen Ti is close to 930 K far from commonly recognized value of 400 K.
Contrast to this “ Temperature Inversion “ is something else. temperature inversion, a reversal of the normal behaviour of temperature in the troposphere (the region of the atmosphere nearest the Earth’s surface), in which a layer of cool air at the surface is overlain by a layer of warmer air. (Under normal conditions air temperature usually decreases with height.) Inversions play an important role in determining cloud forms, precipitation, and visibility. An inversion acts as a cap on the upward movement of air from the layers below. As a result, convection produced by the heating of air from below is limited to levels below the inversion. Diffusion of dust, smoke, and other air pollutants is likewise limited. In regions where a pronounced low-level inversion is present, convective clouds cannot grow high enough to produce showers and, at the same time, visibility may be greatly reduced below the inversion, even in the absence of clouds, by the accumulation of dust and smoke particles. Because air near the base of an inversion tends to be cool, fog is frequently present there.
3 ) Critical Temperature - The critical temperature of a substance is the temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied.
Every substance has a critical temperature. Some examples are shown below.
NH3 132C , Oxygen - 119 C , Carbondioxide 31.2 C, Water 374 C
4 ) Eutectic Temperature or Eutectic Point - lowest possible temperature of solidification for any mixture of specified constituents. Used especially of an alloy whose melting point is lower than that of any other alloy composed of the same constituents in different proportions. The word "eutectic" comes from Greek and means "easily melted". The eutectic mixture has the lowest melting point (which is, of course, the same as the freezing point) of any mixture of
metals, meaning Alloys. The temperature at which the eutectic mixture freezes or melts is known as the eutectic temperature.
There are calculations available for Eutectic Temperatures of various kinds of Alloys.
5 ) Anotine Temperature or Least temperature in clausius-clapeyron equation for Vapour Pressure – Cox temperature - Warmer air can hold more water vapor at equilibrium than colder air. Air that holds this equilibrium amount is saturated. If air is cooled below the saturation temperature, some of the water vapor condenses into liquid, which releases latent heat and warms the air. The Clausius-Clapeyron equation relates the latent heat (heat of transformation ) of vaporization or condensation to the rate of change of vapour pressure with temperature. Or, in the case of a solid-liquid transformation, it relates the latent heat of fusion or solidification to the rate of change of melting point with pressure. Air can hold any proportion of water vapor. However, for humidities greater than a threshold called the saturation humidity, water vapor tends to condense into liquid faster than it re-evaporates. This condensation process lowers the humidity toward the equilibrium (saturation) value. The process is so fast that humidities rarely exceed the equilibrium value. Thus, while air can hold any portion of water vapor, the threshold is rarely exceeded by more than 1% in the real atmosphere. At a given temperature, the vapor pressure of a pure compound is the pressure at which vapor and liquid coexist at equilibrium. The term "vapor pressure" should be used only with pure compounds and is usually considered as a liquid (rather than a gas) property. For a pure compound, there is only one vapor pressure at any temperature. Thus saturation vapor pressure es is a function of temperature, such that es(T). The vapor pressure e of an air parcel is the measure of the moisture content, while the saturation vapor pressure is a function of temperature. Frost point temperature, TF, can be defined as the temperature a parcel of air can be cooled isobarically to form frost. If the dew-point is greater than 0oC, the frost point cannot be defined. But at temperature where the dewpoint is <0oC, the frost point will be higher than the dewpoint. Thus, the general frost is not formed by dew freezing, since as air cooled below freezing the frost point will be reached before the dew point. Clausius-Clapeyron equation can also be applied to obtain the water vapor pressure with respect to supercooled water at temperatures below 0 deg C. As long as no ice is present, the supercooled water is in equilibrium with the water vapor.
Specific heat of water is 2% larger at 30 deg Celsius than the value at 0 deg Celsius. Below -12 deg Celsius the clothes will not dry at all. Bergeron-Findeisen process describes this.
Also be aware of Pomeranchuk Effect.
The anomalous character of the melting, or solidification, of the light helium isotope3 He: at a temperature below 0.3°K, the entropy of liquid3 He is less than that of the solid, and heat absorption occurs when the solid phase is formed. According to the Clausius-Clapeyron equation, the dependence of the melting point Tmelt on pressure is in this case also anomalous—that is, as the pressure rises, Tmelt decreases. The effect was theoretically predicted by
I. Ia. Pomeranchuk in 1950 and experimentally detected by the American physicists W. M. Fairbank and G. K. Walters in 1957.
6 ) Boiling Point - The temperature at which the vapor pressure is equal to 1 atm (14.696 psia or 101.32 kPa) is known as the normal boiling point.
7 ) Freezing Point – Melting point - Pure, crystalline solids have a characteristic melting point, the temperature at which the solid melts to become a liquid. The transition between the solid and the liquid is so sharp for small samples of a pure substance that melting points can be measured to 0.1oC. The melting point of solid oxygen, for example, is -218.4oC.
It is difficult, if not impossible, to heat a solid above its melting point because the heat that enters the solid at its melting point is used to convert the solid into a liquid. It is possible, however, to cool some liquids to temperatures below their freezing points without forming a solid. When this is done, the liquid is said to be supercooled.
An example of a supercooled liquid can be made by heating solid sodium acetate trihydrate (NaCH3CO2 3 H2O). When this solid melts, the sodium acetate dissolves in the water that was trapped in the crystal to form a solution. When the solution cools to room temperature, it should solidify. But it often doesn't. If a small crystal of sodium acetate trihydrate is added to the liquid, however, the contents of the flask solidify within seconds.
A liquid can become supercooled because the particles in a solid are packed in a regular structure that is characteristic of that particular substance.
Some of these solids form very easily; others do not. Some need a particle of dust, or a seed crystal, to act as a site on which the crystal can grow. In order to form crystals of sodium acetate trihydrate, Na+ ions, CH3CO2- ions, and water molecules must come together in the proper orientation. It is difficult for these particles to organize themselves, but a seed crystal can provide the framework on which the proper arrangement of ions and water molecules can grow.
8 ) Curie Temperature - Curie point, also called Curie Temperature, temperature at which certain magnetic materials undergo a sharp change in their magnetic properties. the temperature above which a ferromagnetic substance loses its ferromagnetism and becomes paramagnetic. In the case of rocks and minerals, remanent magnetism appears below the Curie point—about 570° C (1,060° F) for the common magnetic mineral magnetite. This temperature is named for
the French physicist Pierre Curie, who in 1895 discovered the laws that relate some magnetic properties to change in temperature.
Below the Curie point—for example, 770° C (1,418° F) for iron—atoms that behave as tiny magnets spontaneously align themselves in certain magnetic materials. In ferromagnetic materials, such as pure iron, the atomic magnets are oriented within each microscopic region (domain) in the same direction, so that their magnetic fields reinforce each other. In antiferromagnetic materials, atomic magnets alternate in opposite directions, so that their magnetic fields cancel each other. In ferrimagnetic materials, the spontaneous arrangement is a combination of both patterns, usually involving two different magnetic atoms, so that only partial reinforcement of magnetic fields occurs.
Raising the temperature to the Curie point for any of the materials in these three classes entirely disrupts the various spontaneous arrangements, and only a weak kind of more general magnetic behaviour, called paramagnetism, remains. One of the highest Curie points is 1,121° C (2,050° F) for cobalt.
Temperature increases above the Curie point produce roughly similar patterns of decreasing paramagnetism in all three classes of materials. When these materials are cooled below their Curie points, magnetic atoms spontaneously realign so that the ferromagnetism, antiferromagnetism, or ferrimagnetism revives.
The antiferromagnetic Curie point is called the Néel temperature in honour of the French physicist Louis Néel, who in 1936 successfully explained antiferromagnetism.
9 ) Neel Temperature - the temperature above which an antiferromagnetic substance loses its antiferromagnetism and becomes paramagnetic. A temperature, characteristic of certain metals, alloys, and salts, below which spontaneous nonparalleled magnetic ordering takes place so that they become antiferromagnetic, and above which they are paramagnetic. Also known as Néel point. The antiferromagnetic Curie point is called the Néel temperature in honour of the French physicist Louis Néel, who in 1936 successfully explained antiferromagnetism.
10 ) Kindling Temperature - Temperature at which a substance will catch fire and continue to burn is called its ignition point or its kindling point. A substance that can be ignited in the air is said to be flammable (or inflammable). The flash point of a flammable liquid is lower than its ignition point.
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1 ) Krafft Temperature – This is the least known temperature by the students. The Krafft temperature (also known as Krafft point, or critical micelle temperature) is the minimum temperature at which surfactants form micelles. Below the Krafft temperature, there is no value for the critical micelle concentration (CMC), i.e., micelles cannot form. The Krafft temperature is a point of phase change below which the surfactant remains in crystalline form, even in aqueous solution.
Surfactants in such a crystalline state will only solubilize / gather and form micelles if another surfactant assists it in overcoming the forces that keep it crystallized, or if the temperature increases, thus causing entropy to have a stronger force and encouraging the crystalline structure to break apart.
The Krafft point is named after German chemist Friedrich Krafft.
2 ) Inversion Temperature - In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect, Kelvin–Joule effect, or Joule–Thomson expansion) describes the temperature change of a gas or liquid when it is forced through a valve or porous plug while kept insulated so that no heat is exchanged with the environment. This procedure is called a throttling process or Joule–Thomson process.
At room temperature, all gases except hydrogen ( H ), helium ( He ) and neon ( Ne ) cool upon expansion by the Joule–Thomson process. The effect is named after James Prescott Joule and William Thomson, 1st Baron Kelvin, who discovered it in 1852. It followed upon earlier work by Joule on Joule expansion, in which a gas undergoes free expansion in a vacuum and the temperature is unchanged, if the gas is ideal.
The adiabatic (no heat exchanged) expansion of a gas may be carried out in a number of ways. The change in temperature experienced by the gas during expansion depends not only on the initial and final pressure, but also on the manner in which the expansion is carried out.
• If the expansion process is reversible, meaning that the gas is in thermodynamic equilibrium at all times, it is called an isentropic expansion. In this scenario, the gas does positive work during the expansion, and its temperature decreases.
• In a free expansion, on the other hand, the gas does no work and absorbs no heat, so the internal energy is conserved. Expanded in this manner, the temperature of an ideal gas would remain constant, but the temperature of a real gas may either increase or decrease, depending on the initial temperature and pressure.
• The method of expansion discussed in this article, in which a gas or liquid at pressure P1 flows into a region of lower pressure P2 via a valve or porous plug under steady state conditions and without change in kinetic energy, is called the Joule–Thomson process. During this process, enthalpy remains unchanged
The inversion temperature in thermodynamics and cryogenics is the critical temperature below which a non-ideal gas (all gases in reality) that is expanding at constant enthalpy will experience a temperature decrease, and above which will experience a temperature increase. This temperature change is known as the Joule-Thomson effect, and is exploited in the liquefaction of gases. As per the scientific paper that I read, For He Ti is close to 200 ± 50 K, Neon Ti is 870 ± 390 K, Argon Ti 3800 ± 1800 K, For Hydrogen Ti is close to 930 K far from commonly recognized value of 400 K.
Contrast to this “ Temperature Inversion “ is something else. temperature inversion, a reversal of the normal behaviour of temperature in the troposphere (the region of the atmosphere nearest the Earth’s surface), in which a layer of cool air at the surface is overlain by a layer of warmer air. (Under normal conditions air temperature usually decreases with height.) Inversions play an important role in determining cloud forms, precipitation, and visibility. An inversion acts as a cap on the upward movement of air from the layers below. As a result, convection produced by the heating of air from below is limited to levels below the inversion. Diffusion of dust, smoke, and other air pollutants is likewise limited. In regions where a pronounced low-level inversion is present, convective clouds cannot grow high enough to produce showers and, at the same time, visibility may be greatly reduced below the inversion, even in the absence of clouds, by the accumulation of dust and smoke particles. Because air near the base of an inversion tends to be cool, fog is frequently present there.
3 ) Critical Temperature - The critical temperature of a substance is the temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied.
Every substance has a critical temperature. Some examples are shown below.
NH3 132C , Oxygen - 119 C , Carbondioxide 31.2 C, Water 374 C
4 ) Eutectic Temperature or Eutectic Point - lowest possible temperature of solidification for any mixture of specified constituents. Used especially of an alloy whose melting point is lower than that of any other alloy composed of the same constituents in different proportions. The word "eutectic" comes from Greek and means "easily melted". The eutectic mixture has the lowest melting point (which is, of course, the same as the freezing point) of any mixture of
metals, meaning Alloys. The temperature at which the eutectic mixture freezes or melts is known as the eutectic temperature.
There are calculations available for Eutectic Temperatures of various kinds of Alloys.
5 ) Anotine Temperature or Least temperature in clausius-clapeyron equation for Vapour Pressure – Cox temperature - Warmer air can hold more water vapor at equilibrium than colder air. Air that holds this equilibrium amount is saturated. If air is cooled below the saturation temperature, some of the water vapor condenses into liquid, which releases latent heat and warms the air. The Clausius-Clapeyron equation relates the latent heat (heat of transformation ) of vaporization or condensation to the rate of change of vapour pressure with temperature. Or, in the case of a solid-liquid transformation, it relates the latent heat of fusion or solidification to the rate of change of melting point with pressure. Air can hold any proportion of water vapor. However, for humidities greater than a threshold called the saturation humidity, water vapor tends to condense into liquid faster than it re-evaporates. This condensation process lowers the humidity toward the equilibrium (saturation) value. The process is so fast that humidities rarely exceed the equilibrium value. Thus, while air can hold any portion of water vapor, the threshold is rarely exceeded by more than 1% in the real atmosphere. At a given temperature, the vapor pressure of a pure compound is the pressure at which vapor and liquid coexist at equilibrium. The term "vapor pressure" should be used only with pure compounds and is usually considered as a liquid (rather than a gas) property. For a pure compound, there is only one vapor pressure at any temperature. Thus saturation vapor pressure es is a function of temperature, such that es(T). The vapor pressure e of an air parcel is the measure of the moisture content, while the saturation vapor pressure is a function of temperature. Frost point temperature, TF, can be defined as the temperature a parcel of air can be cooled isobarically to form frost. If the dew-point is greater than 0oC, the frost point cannot be defined. But at temperature where the dewpoint is <0oC, the frost point will be higher than the dewpoint. Thus, the general frost is not formed by dew freezing, since as air cooled below freezing the frost point will be reached before the dew point. Clausius-Clapeyron equation can also be applied to obtain the water vapor pressure with respect to supercooled water at temperatures below 0 deg C. As long as no ice is present, the supercooled water is in equilibrium with the water vapor.
Specific heat of water is 2% larger at 30 deg Celsius than the value at 0 deg Celsius. Below -12 deg Celsius the clothes will not dry at all. Bergeron-Findeisen process describes this.
Also be aware of Pomeranchuk Effect.
The anomalous character of the melting, or solidification, of the light helium isotope3 He: at a temperature below 0.3°K, the entropy of liquid3 He is less than that of the solid, and heat absorption occurs when the solid phase is formed. According to the Clausius-Clapeyron equation, the dependence of the melting point Tmelt on pressure is in this case also anomalous—that is, as the pressure rises, Tmelt decreases. The effect was theoretically predicted by
I. Ia. Pomeranchuk in 1950 and experimentally detected by the American physicists W. M. Fairbank and G. K. Walters in 1957.
6 ) Boiling Point - The temperature at which the vapor pressure is equal to 1 atm (14.696 psia or 101.32 kPa) is known as the normal boiling point.
7 ) Freezing Point – Melting point - Pure, crystalline solids have a characteristic melting point, the temperature at which the solid melts to become a liquid. The transition between the solid and the liquid is so sharp for small samples of a pure substance that melting points can be measured to 0.1oC. The melting point of solid oxygen, for example, is -218.4oC.
It is difficult, if not impossible, to heat a solid above its melting point because the heat that enters the solid at its melting point is used to convert the solid into a liquid. It is possible, however, to cool some liquids to temperatures below their freezing points without forming a solid. When this is done, the liquid is said to be supercooled.
An example of a supercooled liquid can be made by heating solid sodium acetate trihydrate (NaCH3CO2 3 H2O). When this solid melts, the sodium acetate dissolves in the water that was trapped in the crystal to form a solution. When the solution cools to room temperature, it should solidify. But it often doesn't. If a small crystal of sodium acetate trihydrate is added to the liquid, however, the contents of the flask solidify within seconds.
A liquid can become supercooled because the particles in a solid are packed in a regular structure that is characteristic of that particular substance.
Some of these solids form very easily; others do not. Some need a particle of dust, or a seed crystal, to act as a site on which the crystal can grow. In order to form crystals of sodium acetate trihydrate, Na+ ions, CH3CO2- ions, and water molecules must come together in the proper orientation. It is difficult for these particles to organize themselves, but a seed crystal can provide the framework on which the proper arrangement of ions and water molecules can grow.
8 ) Curie Temperature - Curie point, also called Curie Temperature, temperature at which certain magnetic materials undergo a sharp change in their magnetic properties. the temperature above which a ferromagnetic substance loses its ferromagnetism and becomes paramagnetic. In the case of rocks and minerals, remanent magnetism appears below the Curie point—about 570° C (1,060° F) for the common magnetic mineral magnetite. This temperature is named for
the French physicist Pierre Curie, who in 1895 discovered the laws that relate some magnetic properties to change in temperature.
Below the Curie point—for example, 770° C (1,418° F) for iron—atoms that behave as tiny magnets spontaneously align themselves in certain magnetic materials. In ferromagnetic materials, such as pure iron, the atomic magnets are oriented within each microscopic region (domain) in the same direction, so that their magnetic fields reinforce each other. In antiferromagnetic materials, atomic magnets alternate in opposite directions, so that their magnetic fields cancel each other. In ferrimagnetic materials, the spontaneous arrangement is a combination of both patterns, usually involving two different magnetic atoms, so that only partial reinforcement of magnetic fields occurs.
Raising the temperature to the Curie point for any of the materials in these three classes entirely disrupts the various spontaneous arrangements, and only a weak kind of more general magnetic behaviour, called paramagnetism, remains. One of the highest Curie points is 1,121° C (2,050° F) for cobalt.
Temperature increases above the Curie point produce roughly similar patterns of decreasing paramagnetism in all three classes of materials. When these materials are cooled below their Curie points, magnetic atoms spontaneously realign so that the ferromagnetism, antiferromagnetism, or ferrimagnetism revives.
The antiferromagnetic Curie point is called the Néel temperature in honour of the French physicist Louis Néel, who in 1936 successfully explained antiferromagnetism.
9 ) Neel Temperature - the temperature above which an antiferromagnetic substance loses its antiferromagnetism and becomes paramagnetic. A temperature, characteristic of certain metals, alloys, and salts, below which spontaneous nonparalleled magnetic ordering takes place so that they become antiferromagnetic, and above which they are paramagnetic. Also known as Néel point. The antiferromagnetic Curie point is called the Néel temperature in honour of the French physicist Louis Néel, who in 1936 successfully explained antiferromagnetism.
10 ) Kindling Temperature - Temperature at which a substance will catch fire and continue to burn is called its ignition point or its kindling point. A substance that can be ignited in the air is said to be flammable (or inflammable). The flash point of a flammable liquid is lower than its ignition point.
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