Introduction to Physical Chemistry – Lecture 7
... Regarding the Third Law, this simply allows us to pick a reference point where an absolute value of entropy can be assigned. The law dS = (δQ/T )rev only allows us to compute changes in entropy. The Third Law says that at 0 K a perfect crystal has no entropy. This makes sense, since an object at 0 K ...
... Regarding the Third Law, this simply allows us to pick a reference point where an absolute value of entropy can be assigned. The law dS = (δQ/T )rev only allows us to compute changes in entropy. The Third Law says that at 0 K a perfect crystal has no entropy. This makes sense, since an object at 0 K ...
L 04 Heat transfer
... = 5.67010-8 W/(m2K4) is Stefan – Boltzmann constant, - dimensionless emissivity coefficient (the fraction of the ideal blackbody spectrum energy which a real body actually emits), T - absolute temperature of the body, K. Surface material Ideal blackbody Black paint Concrete Polished aluminum f ...
... = 5.67010-8 W/(m2K4) is Stefan – Boltzmann constant, - dimensionless emissivity coefficient (the fraction of the ideal blackbody spectrum energy which a real body actually emits), T - absolute temperature of the body, K. Surface material Ideal blackbody Black paint Concrete Polished aluminum f ...
Measuring Temperature
... Heat depends on temperature, but also on the mass of the object, and its heat capacity. Even though Lake Ontario is at a colder temperature than your cup of coffee, it contains a lot more heat. The reason is that Lake Ontario is so much bigger (more massive) than your morning beverage. ...
... Heat depends on temperature, but also on the mass of the object, and its heat capacity. Even though Lake Ontario is at a colder temperature than your cup of coffee, it contains a lot more heat. The reason is that Lake Ontario is so much bigger (more massive) than your morning beverage. ...
Convective heat transfer
... either be zero or have nonzero values, but all derivatives of temperature at any point with respect to time are uniformly zero. In steady state conduction, the amount of heat entering any region of an object is equal to amount of heat coming out (if this were not so, the temperature would be rising ...
... either be zero or have nonzero values, but all derivatives of temperature at any point with respect to time are uniformly zero. In steady state conduction, the amount of heat entering any region of an object is equal to amount of heat coming out (if this were not so, the temperature would be rising ...
Principle of minimum Energy The second law of thermodynamics
... A system that is isothermal with a bath, and that can only exchange heat but NO WORK will try to minimize its free energy F. Any isothermal process that increases the internal never occur spontaneously. Irreversible isothermal process happens spontaneously until dF = 0 (F reaches a minimum) Using th ...
... A system that is isothermal with a bath, and that can only exchange heat but NO WORK will try to minimize its free energy F. Any isothermal process that increases the internal never occur spontaneously. Irreversible isothermal process happens spontaneously until dF = 0 (F reaches a minimum) Using th ...
1 Lecture: 2 Thermodynamic equilibrium 1
... This situation is called “Chemical Equilibrium” We will give more detailed description of the chemical equilibrium later on in this curse. A system that is in mechanical, thermal and chemical equilibrium at the same time is said to be in thermodynamic equilibrium. Functions of state When a system is ...
... This situation is called “Chemical Equilibrium” We will give more detailed description of the chemical equilibrium later on in this curse. A system that is in mechanical, thermal and chemical equilibrium at the same time is said to be in thermodynamic equilibrium. Functions of state When a system is ...
Black-body radiation
Black-body radiation is the type of electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body (an opaque and non-reflective body) held at constant, uniform temperature. The radiation has a specific spectrum and intensity that depends only on the temperature of the body.The thermal radiation spontaneously emitted by many ordinary objects can be approximated as blackbody radiation. A perfectly insulated enclosure that is in thermal equilibrium internally contains black-body radiation and will emit it through a hole made in its wall, provided the hole is small enough to have negligible effect upon the equilibrium.A black-body at room temperature appears black, as most of the energy it radiates is infra-red and cannot be perceived by the human eye. Because the human eye cannot perceive color at very low light intensities, a black body, viewed in the dark at the lowest just faintly visible temperature, subjectively appears grey (but only because the human eye is sensitive only to black and white at very low intensities - in reality, the frequency of the light in the visible range would still be red, although the intensity would be too low to discern as red), even though its objective physical spectrum peaks in the infrared range. When it becomes a little hotter, it appears dull red. As its temperature increases further it eventually becomes blindingly brilliant blue-white.Although planets and stars are neither in thermal equilibrium with their surroundings nor perfect black bodies, black-body radiation is used as a first approximation for the energy they emit.Black holes are near-perfect black bodies, in the sense that they absorb all the radiation that falls on them. It has been proposed that they emit black-body radiation (called Hawking radiation), with a temperature that depends on the mass of the black hole.The term black body was introduced by Gustav Kirchhoff in 1860. When used as a compound adjective, the term is typically written as hyphenated, for example, black-body radiation, but sometimes also as one word, as in blackbody radiation. Black-body radiation is also called complete radiation or temperature radiation or thermal radiation.